Resist curable resin composition and cured article thereof

ABSTRACT

A resist curable resin material composed mainly of a curable prepolymer (for example, a photocurable resin material comprising a photosensitive prepolymer having an ethylenically unsaturated terminal group originating in an acrylic monomer (A), a compound having an ethylenically unsaturated group excluding the photosensitive prepolymer (B), and a photopolymerization initiator (C)) and a flame-retarding agent containing a hydrated metal compound and a brominated epoxy compound are mixed to produce a resist curable resin composition. Alternatively, the resist curable resin material described above and a hydrated metal compound surface-treated with a surface treating agent having an amphipathic property and a polarity are mixed to produce a resist curable resin composition.

This application claims the benefit pursuant to 35 U.S.C. §109 (e)(1) ofU.S. Provisional Applications No. 60/304,428 filed on Jul. 12, 2001 andNo. 60/330,816 filed on Oct. 31, 2001.

TECHNICAL FIELD

The present invention relates to a resist curable resin composition forforming a protective film, which is used to produce a printed circuitboard, and use thereof.

BACKGROUND ART

In the manufacture of printed circuit boards, various substrateprotecting means, such as resist used in the etching step and solderresist used in the soldering step, have conventionally been required.Also in the manufacturing process of a film-like printed circuit board(flexible printed circuit board abbreviated as FPC) used in smallequipment, a solder resist for protecting independent wirings isrequired in the soldering step for mounting parts.

As a protective means for these substrates, there has conventionallybeen used a cover-layer for laminating those obtained by punching out apolyimide film into a predetermined shape, or a cover-coat made of aheat-resistant material for applying ink. This cover-layer or cover-coatalso serves as a protective film for wirings after soldering andrequires heat resistance during soldering, insulating properties, andsufficient pliability so as not to crack when folded duringincorporation of a substrate. An FPC used for purposes other thanbattery driving equipment also requires flame resistance, and thosehaving good balance with the pliability are required.

The cover-layer formed by punching out the polyimide film meets theabove prescribed properties and is used most popularly at present, buthas a problem in that the punching out step requires an expensive moldand manual positioning and lamination of the punched out film increasethe cost, and moreover, a micropattern is difficult to form. Thecover-coat has such a problem in that the manufacturing cost increasesbecause screen printing requires a drying step and the operatabilitybecomes worse.

To solve these problems, there has been proposed a method of applying aphotosensitive resin composition on a substrate in the form of a liquidor laminating it in the form of a film. According to this method, sincea cover-coat or cover-layer of a micropattern can be easily formed byforming a coating on the substrate and subjecting to the exposure,development, and heating steps using a photographical technique, variousphotosensitive resin compositions have conventionally been developed.

However, no conventional photosensitive resin composition met all theproperties required for an FPC. For example, a photosensitive resincomposition comprising a prepolymer obtained by the addition reaction ofa novolak type epoxy vinyl ester resin and a polybasic anhydride, aphotopolymerization initiator, a diluent and an epoxy compound has beenproposed (Japanese Exampled Patent Application, Second Publication No.1-54390). This photosensitive resin composition had good heat resistanceand insulating properties, but is not suited for use in an FPC becauseof poor pliability. Also, there has been proposed a photosensitive resincomposition prepared by mixing a binder system composed of alow-molecular weight copolymer (which is a reaction product of acopolymer formed from an ethylenically unsaturated dicarboxylicanhydride and an ethylenically unsaturated comonomer, and an amine) anda carboxylic acid-containing high-molecular weight copolymer with anacrylated urethane monomer component, a photoinitiator and a blockpolyisocyanate crosslinking agent (Japanese Unexamined PatentApplication, First Publication No. 7-278492). However, thisphotosensitive resin composition had a problem that the use is limitedbecause of its poor flame resistance.

As a method of imparting the flame resistance to the photosensitiveresin composition, there have conventionally been used a method of usinga halide-based flame retardant such as brominated epoxy resin and amethod of using a flame retardant of a combination of the halide-basedflame retardant and an auxiliary flame retardant such as antimonytrioxide (Japanese Unexamined Patent Application, First Publication No.9-325490, and Japanese Unexamined Patent Application, First PublicationNo. 11-242331). However, these flame retardants are inferior inreliability in a high temperature environment and, when using anantimony compound, it is necessary to take into account environmentalproblems with respect to waste disposal of the resin. Furthermore, thebrominated epoxy resin had a problem in that the pliability is impairedwhen incorporating it in a sufficient amount to obtain a satisfactoryflame-retarding effect.

Also, methods of using a phosphate ester as the flame retardant havebeen proposed (Japanese Unexamined Patent Application, First PublicationNo. 9-235449, Japanese Unexamined Patent Application, First PublicationNo. 10-306201, and Japanese Unexamined Patent Application, FirstPublication No. 11-271967). However, a poor flame-retarding effect isexerted by using only the phosphate ester, and it is impossible tosufficiently meet criteria of the flame resistance according to the ULStandard.

As described above, it is not easy to obtain a resist film, which hasboth high flame resistance and pliability capable of meeting criteriaaccording to the UL Standard and is also superior in soldering heatresistance, moisture resistance, high temperature reliability,photosensitivity, and developability. Therefore, a further improvementhas been required.

DISCLOSURE OF INVENTION

An object of the present invention is to provide a resist curable resincomposition, which has both high-level flame resistance and pliabilityand is superior in soldering heat resistance, moisture resistance, hightemperature reliability, photosensitivity and developability, and alsohas good transparency, particularly a resist curable resin compositionwhich is suited for use as a cover-layer or solder resist for an FPC.

Another object of the present invention is to provide a preferred methodfor forming a heat-resistant protective film using the resist curableresin composition described above.

The present inventors have intensively studied and found that theproblems described above can be solved by using a flame-retarding agenthaving a specific composition, and thus the present invention has beencompleted.

The present invention provides a resist curable resin compositioncomprising a resist curable resin material and a hydrated metalcompound.

The first aspect of the present invention is a resist curable resincomposition wherein a brominated epoxy compound is incorporated into theconstitution described above.

According to the aspect described above, a resist curable resincomposition having excellent flame resistance, photosensitivity,developability, pliability, and soldering heat resistance is obtained.

The second aspect of the present invention is a resist curable resincomposition wherein the hydrated metal compound is surface-treated witha surface treating agent having at least one of an amphipathic propertyand a polarity.

According to the aspect described above, a resist curable resincomposition having excellent flame resistance, photosensitivity,developability, and folding resistance is obtained.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in detail below.

A resist curable resin composition as the first embodiment of thepresent invention comprises a resist curable resin material and a flameretarder.

I-1. Resist Curable Resin Material

The resist curable resin material used in the first embodiment is mainlycomposed of a curable prepolymer. As used herein, the curable resinmaterial may be any curable material which is used as a resist resinmaterial such as a photocurable resin material, an electron beam curableresin material, an X-ray curable resin material, or a thermocurableresin material.

(i) Photocurable Resin Material

The photocurable resin material is not specifically limited as long asit can be cured by visible light, ultraviolet light, or the like, andpreferably comprises a photosensitive prepolymer having an ethylenicallyunsaturated terminal group originating in an acrylic monomer (A-1), acompound having an ethylenically unsaturated group (B) excluding thephotosensitive prepolymer (A-1), and a photopolymerization initiator(C).

(1) Photosensitive Prepolymer (A-1)

The photosensitive prepolymer (A-1) used in the first embodiment has anethylenically unsaturated terminal group originating in an acrylicmonomer. As used herein, the acrylic monomer is acrylic acid ormethacrylic acid (hereinafter acrylic acid and methacrylic acid aregenerically referred to as “(meth)acrylic acid”) or a derivative thereofsuch as alkyl ester or hydroxyalkyl ester.

The photosensitive prepolymer (A-1) as the first embodiment is notspecifically limited as long as it meets the conditions described above,and specific examples thereof include polyester acrylate, epoxyacrylate, urethane acrylate, polybutadiene acrylate, silicone acrylate,and melamine acrylate. Among these, epoxy acrylate and urethane acrylateare preferred.

Those having at least one carboxyl group and two ethylenicallyunsaturated bonds in a molecule are more preferred. Specific examples ofparticularly preferred one include epoxy (meth)acrylate compound havinga carboxyl group (EA) and urethane (meth)acrylate compound having acarboxyl group (UA).

<Epoxy (Meth)Acrylate Compound Having a Carboxyl Group (EA)>

The epoxy (meth)acrylate compound having a carboxyl group in the firstembodiment is not specifically limited, and for example, an epoxy(meth)acrylate compound obtained by reacting a reaction product of anepoxy compound and an unsaturated group-containing monocarboxylic acidwith an acid anhydride is preferred.

The epoxy compound is not specifically limited, and examples thereofinclude epoxy compounds such as bisphenol A type epoxy compound,bisphenol F type epoxy compound, bisphenol S type epoxy compound, phenolnovolak type epoxy compound, cresol novolak type epoxy compound, oraliphatic epoxy compound. These epoxy compounds can be used alone, ortwo or more kinds of them can be used in combination.

Examples of the unsaturated group-containing monocarboxylic acid includeacrylic acid, dimer of acrylic acid, methacrylic acid, β-furfurylacrylicacid, β-styrylacrylic acid, cinnamic acid, crotonic acid,α-cyanocinnamic acid, and the like. It further includes a hemiestercompound as a reaction product of a hydroxyl group-containing acrylatesuch as hydroxyalkyl ester of (meth)acrylic acid and a saturated orunsaturated dibasic acid anhydride, or a hemiester compound as areaction product of an unsaturated group-containing monoglycidyl etherand a saturated or unsaturated dibasic acid anhydride. These unsaturatedgroup-containing monocarboxylic acids can be used alone, or two or morekinds of them can be used in combination.

Examples of the acid anhydride include dibasic acid anhydride such asmaleic anhydride, succinic anhydride, itaconic anhydride, phthalicanhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride,methylhexahydrophthalic anhydride, endomethylenetetrahydrophthalicanhydride, methylendomethylenetetrahydrophthalic anhydride, chlorendicanhydride, or methyltetrahydrophthalic anhydride; aromatic polyhydriccarboxylic anhydride such as trimellitic anhydride, pyromelliticanhydride, or benzophenonetetracarboxylic dianhydride; and polyhydriccarboxylic anhydride derivative such as5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylicanhydride, or endobicyclo-[2,2,1]-hept-5-ene-2,3-dicarboxylic anhydride.These acid anhydrides can be used alone, or two or more kinds of themcan be used in combination.

The molecular weight of the epoxy (meth)acrylate compound having acarboxyl group thus obtained is not specifically limited, but thenumber-average molecular weight is preferably within a range from 1,000to 40,000, and more preferably from 2,000 to 5,000. As used herein, thenumber-average molecular weight is a value as measured by a gelpermeation chromatograph relative to polystyrene standards.

The acid value (which means an acid value of the solid content) of theepoxy (meth)acrylate compound is preferably 10 mg KOH/g or more, morepreferably within a range from 45 mg KOH/g to 160 mg KOH/g, andparticularly preferably from 50 mg KOH/g to 140 mg KOH/g because of goodbalance between the alkali solubility and the alkali resistance of thecured film. When the acid value is less than 10 mg KOH/g, the alkalisolubility becomes poor. On the other hand, when the acid value is toolarge, the alkali resistance of the cured film and characteristics as aresist such as electrical characteristics are sometimes lowered,depending on the combination of constituent components of the resistcurable resin composition.

The epoxy (meth)acrylate compound having a carboxyl group may be usedalone, thereby to constitute the photosensitive prepolymer (A-1), butmay be used in combination with a urethane (meth)acrylate compoundhaving a carboxyl group described hereinafter. In that case, the epoxy(meth)acrylate compound having a carboxyl group is preferably used in anamount of 100 parts by weight or less based on 100 parts by weight ofthe urethane (meth)acrylate compound having a carboxyl group.

<Urethane (Meth)Acrylate Compound Having a Carboxyl Group (UA)>

The urethane (meth)acrylate compound having a carboxyl group in thefirst embodiment is a compound containing a unit originating in a(meth)acrylate having a hydroxyl group, a unit originating in a polyoland a unit originating in a polyisocyanate as a constituent unit. Morespecifically, it is a compound having such a structure that bothterminals are composed of a unit originating in a (meth)acrylate havinga hydroxyl group and a portion between both terminals is composed of arepeating unit comprising a unit originating in a polyol and a unitoriginating in a polyisocyanate, which are linked with a urethane bond,and carboxyl groups exist in this repeating unit.

That is, the urethane (meth)acrylate compound having a carboxyl group isrepresented by the formula: Ra—(ORbO—OCNHRcNHCO)_(n)—Ra [wherein Rarepresents a unit originating in a (meth)acrylate having a hydroxylgroup, ORbO represents a dehydrogenated residue of a polyol, and Rcrepresents a deisocyanated residue of a polyisocyanate].

The urethane (meth)acrylate compound having a carboxyl group can beprepared by reacting a (meth)acrylate having at least a hydroxyl group,a polyol and a polyisocyanate. It is necessary to use a compound havinga carboxyl group as the polyol or polyisocyanate. Preferably, a polyolhaving a carboxyl group is used. The use of the compound having acarboxyl group as the polyol and/or polyisocyanate makes it possible toprepare a urethane (meth)acrylate compound wherein carboxyl groups existin Rb or Rc. In the formula described above, n is preferably from about1 to 200, and more preferably from 2 to 30. When n is within such arange, the cured film made of the resist curable resin composition ismore superior in pliability.

When using two or more kinds of at least one of the polyol andpolyisocyanate, the repeating unit represent plural kinds and theregularity of plural units can be appropriately selected according topurposes such as complete random, block, localization, and the like.

Examples of the (meth)acrylate having a hydroxyl group used in theurethane (meth)acrylate compound having a carboxyl group (UA) include2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate,hydroxybutyl (meth)acrylate, caprolactone or alkylene oxide adduct ofthe respective (meth)acrylates described above, glycerinmono(meth)acrylate, glycerin di(meth)acrylate, glycidyl methacrylateacrylic acid adduct, trimethylolpropane mono(meth)acrylate, trimethyloldi(meth)acrylate, pentaerythritol tri(meth)acrylate,dipentaerythritolpenta(meth)acrylate, ditrimethylolpropanetri(meth)acrylate, and trimethylolpropane alkylene oxideadduct-di(meth)acrylate.

These (meth)acrylates having a hydroxyl group can be used alone, or twoor more kinds of them can be used in combination. Among these(meth)acrylates having a hydroxyl group, 2-hydroxyethyl (meth)acrylate,hydroxypropyl (meth)acrylate and hydroxybutyl (meth)acrylate arepreferred, and 2-hydroxyethyl (meth)acrylate is more preferred. Whenusing 2-hydroxyethyl (meth)acrylate, it is easier to synthesize theurethane (meth)acrylate compound having a carboxyl group (UA).

As the polyol used in the urethane (meth)acrylate compound having acarboxyl group (UA), a polymer polyol and/or a dihydroxyl compound canbe used. Examples of the polymer polyol include polyether-based diolsuch as polyethylene glycol, polypropylene glycol, or polytetramethyleneglycol; polyester-based polyol obtained from an ester of a polyhydricalcohol and a polybasic acid; polycarbonate-based diol containing a unitoriginating in hexamethylene carbonate or pentamethylene carbonate as aconstituent unit; and polylactone-based diol such aspolycaprolactonediol or polybutyrolactonediol.

When using the polymer polyol having a carboxyl group, there can be useda compound synthesized by making carboxyl groups to remain bysynthesizing the polymer polyol in the co-presence of a tri- orpolyvalent polybasic acid such as (anhydrous) trimellitic acid.

These polymer polyols can be used alone, or two or more kinds of themcan be used in combination. When using polymer polyols having anumber-average molecular weight of 200 to 2,000, the cured film made ofthe resist curable resin composition is more superior in pliability.Therefore, it is preferred. When using polycarbonate diol among thesepolymer polyols, the cured film made of the resist curable resincomposition has high heat resistance and is superior in pressure cookerresistance. Therefore, it is preferred. When the constituent unit of thepolymer polyol is not composed of only a single constituent unit, but iscomposed of plural constituent units, the cured film made of the resistcurable resin composition is more superior in pliability. Therefore, itis preferred. Examples of the polymer polyol composed of pluralconstituent units include polyether-based diol containing unitsoriginating in ethylene glycol and propylene glycol as a constituentunit, and polycarbonate diol containing units originating inhexamethylene carbonate and pentamethylene carbonate as a constituentunit.

As the dihydroxyl compound, a branched or straight-chain compound havingtwo alcoholic hydroxyl groups can be used. It is particularly preferredto use an aliphatic dihydroxycarboxylic acid having a carboxyl group.Examples of the dihydroxyl compound include dimethylolpropionic acid anddimethylolbutanoic acid. By using the aliphatic dihydroxycarboxylic acidhaving a carboxyl group, it is possible to easily make carboxyl groupsto exist in the urethane (meth)acrylate compound.

These dihydroxyl compounds can be used alone, or two or more kinds ofthem may be used in combination or be used in combination with thepolymer polyol.

When using the polymer polyol having a carboxyl group in combination orusing those having a carboxyl group as polyisocyanate describedhereinafter, there can be used a dihydroxyl compound having no carboxylgroup, such as ethylene glycol, diethylene glycol, propylene glycol,1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, neopentyl glycol,3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, orhydroquinone.

Specific examples of the polyisocyanate used in the urethane(meth)acrylate compound having a carboxyl group (UA) includediisocyanate such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate,isophorone diisocyanate, hexamethylene diisocyanate, diphenylmethylenediisocyanate, (o, m, or p)-xylene diisocyanate,methylenebis(cyclohexylisocyanate), trimethylhexamethylene diisocyanate,cyclohexane-1,3-dimethylene diisocyanate, cyclohexane-1,4-dimethylenediisocyanat, or 1,5-naphthalene diisocyanate. These polyisocyanates canbe used alone, or two or more kinds of them can be used in combination.A polyisocyanate having a carboxyl group can also be used.

The molecular weight of the urethane (meth)acrylate compound having acarboxyl group (UA) used in the first embodiment is not specificallylimited, but the number-average molecular weight of the urethane(meth)acrylate compound (UA) is preferably within a range from 1,000 to40,000, and more preferably from 8,000 to 30,000. As used herein, thenumber-average molecular weight is a value as measured by gel permeationchromatography relative to polystyrene standards. The acid value of theurethane (meth)acrylate is preferably within a range from 5 to 150 mgKOH/g, and more preferably from 30 to 120 mg KOH/g.

When the number-average molecular weight of the urethane (meth)acrylatecompound having a carboxyl group is less than 1,000, the elongation andstrength of the cured film made of the resist curable resin compositionare sometimes impaired. On the other hand, when the number-averagemolecular weight exceeds 40,000, the pliability is likely to be loweredbecause the cured film becomes too hard. When the acid value is lessthan 5 mg KOH/g, the alkali solubility of the resist curable resincomposition becomes poor, sometimes. On the other hand, when the acidvalue exceeds 150 mg KOH/g, the alkali resistance and electricalcharacteristics of the cured film become poor, sometimes.

The acid value of the urethane (meth)acrylate compound having a carboxylgroup is preferably within a range from 5 to 150 mg KOH. Even if theacid value is within the range described above, the developability isimproved by increasing the acid value; however, the pliability tends tobe lowered. When the acid value is decreased, the pliability isenhanced; however, the developability is lowered and development residuetends to be formed. In that case, when using at least two kinds ofurethane (meth)acrylate compounds having a carboxyl group, which havedifferent acid values, in combination, a resist curable resincomposition having excellent pliability and good developability can beeasily obtained, sometimes.

It is particularly preferred to use at least one kind of a urethane(meth)acrylate compound having a carboxyl group having an acid value of5 mg KOH/g or more and less than 60 mg KOH/g (hereinafter referred to asa “urethane (meth)acrylate compound (a)”) and a urethane (meth)acrylatecompound having a carboxyl group, which has an acid value of 60 mg KOH/gor more and 150 mg KOH/g or less (hereinafter referred to as a “urethane(meth)acrylate compound (b)”) in combination.

When using urethane (meth)acrylate compounds having a carboxyl group,which have different acid values, in combination, a weight ratio of theurethane (meth)acrylate compound (a) to the urethane (meth)acrylatecompound (b) is preferably 40–90:60–10 (100 in total) in 100 parts byweight of the urethane (meth)acrylate compound having a carboxyl group(UA). It is particularly preferred to use an excess amount of theurethane (meth)acrylate compound (a), and a weight ratio of the urethane(meth)acrylate compound (a) to the urethane (meth)acrylate compound (b)is more preferably within a range from 60–90:40–10.

The urethane (meth)acrylate compound having a carboxyl group can beprepared by (1) a method of mixing and reacting a (meth)acrylate havinga hydroxyl group, a polyol and a polyisocyanate at a time, (2) a methodof reacting a polyol with a polyisocyanate to prepare a urethaneisocyanate prepolymer having one or more isocyanate groups in a moleculeand reacting the urethane isocyanate prepolymer with a (meth)acrylatehaving a hydroxyl group, or (3) a method of reacting a (meth)acrylatehaving a hydroxyl group with a polyisocyanate to prepare a urethaneisocyanate prepolymer having one or more isocyanate groups in a moleculeand reacting the prepolymer with a polyol.

(2) Compound Having an Ethylenically Unsaturated Group (B)

The compound having an ethylenically unsaturated group contained in thephotocuring component in the resist curable resin composition is otherthan the photosensitive prepolymer (A-1) and is used for the purpose ofcontrolling the viscosity of the resist curable resin composition, orcontrolling physical properties such as heat resistance and pliabilitywhen the cured article is made from the resist curable resincomposition. Preferably, a (meth)acrylate ester is used.

Specific examples thereof include alkyl(meth)acrylate such as methyl(meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl(meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate,tert-butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate,isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl(meth)acrylate, lauryl (meth)acrylate, or stearyl (meth)acrylate;alicyclic (meth)acrylate such as cyclohexyl (meth)acrylate, bomyl(meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl(meth)acrylate, or dicyclopentenyloxyethyl (meth)acrylate; aromatic(meth)acrylate such as benzyl (meth)acrylate, phenyl (meth)acrylate,phenylcarbitol (meth)acrylate, nonylphenyl (meth)acrylate,nonylphenylcarbitol (meth)acrylate, or nonylphenoxy (meth)acrylate;(meth)acrylate having a hydroxyl group, such as 2-hydroxyethyl(meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl(meth)acrylate, butanediolmono (meth)acrylate, glycerol (meth)acrylate,phenoxyhydroxypropyl (meth)acrylate, polyethylene glycol (meth)acrylate,or glycerol di(meth)acrylate; (meth)acrylate having an amino group, suchas 2-dimethylaminoethyl (meth)acrylate, 2-diethylaminoethyl(meth)acrylate, or 2-tert-butylaminoethyl (meth)acrylate; methacrylatehaving a phosphorus atom, such as methacryloxyethyl phosphate, bismethacryloxyethyl phosphate, or methacryloxyethylphenyl acid phosphate(phenyl P); diacrylate such as ethylene glycol di(meth)acrylate,diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate,tetraethylene di(meth)acrylate, polyethylene glycol di(meth)acrylate,propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate,tripropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate,1,3-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate,1,6-hexanediol di(meth)acrylate, or bis glycidyl (meth)acrylate;polyacrylate such as trimethylolpropane tri(meth)acrylate,pentaerythritol tri(meth)acrylate, or dipentaerythritolhexa(meth)acrylate; modified polyol polyacrylate such as diacrylatemodified with 4 mol of ethylene oxide of bisphenol S, diacrylatemodified with 4 mol of ethylene oxide of bisphenol A, fattyacid-modified pentaerythritol diacrylate, triacrylate modified with 3mol of propylene oxide of trimethylolpropane, or triacrylate modifiedwith 6 mol of propylene oxide of trimethylolpropane; poly acrylatehaving an isocyanuric acid skeleton, such asbis(acryloyloxyethyl)monohydroxyethyl isocyanurate,tris(acryloyloxyethyl) isocyanurate, or ε-caprolactone-modifiedtris(acryloyloxyethyl) isocyanurate; polyester acrylate such asα,ω-diacryloyl-(bisethylene glycol)-phthalate orα,ω-tetraacryloyl-(bistrimethylolpropane)-tetrahydrophthalate; glycidyl(meth)acrylate; allyl (meth)acrylate; ω-hydroxyhexanoyloxyethyl(meth)acrylate; polycaprolactone (meth)acrylate; (meth)acryloyloxyethylphthalate; (meth)acryloyloxyethyl succinate; 2-hydroxy-3-phenoxypropylacrylate; and phenxyethyl acrylate.

Also an N-vinyl compound such as N-vinylpyrrolidone, N-vinylformamide,or N-vinylacetamide, polyester acrylate, urethane acrylate, and epoxyacrylate can be preferably used as a compound having an ethylenicallyunsaturated group.

Among these compounds, (meth)acrylate having a hydroxyl group, glycidyl(meth)acrylate and urethane acrylate are preferred. Examples of the(meth)acrylate having a hydroxyl group include 2-hydroxyethyl(meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl(meth)acrylate, and urethane acrylate. Those having three or moreethylenilcally unsaturated groups are preferred because the heatresistance is enhanced.

A mixing ratio of the photosensitive prepolymer (A-1) to the compoundhaving an ethylenically unsaturated group (B), that is, a weight ratio(A-1):(B) is preferably within a range from 95:5 to 50:50, preferablyfrom 90:10 to 60:40, and more preferably from 85:15 to 70:30 (100 intotal). When the amount of the component (A-1) exceeds 95% by weight,the soldering heat resistance of the cured film made of the resistcurable resin composition is sometimes lowered. On the other hand, whenthe amount of the component (A-i) is less than 50% by weight, the alkalisolubility of the resist curable resin composition tends to be lowered.

(3) Photopolymerization Initiator (C)

Examples of the photopolymerization initiator (C) used in the firstembodiment include benzophenones such as benzophenone, benzoylbenzoicacid, 4-phenylbenzophenone, hydroxybenzophenone, and4,4′-bis(diethylamino)benzophenone; benzoin alkyl ethers such asbenzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropylether, benzoinbutyl ether, and benzoin isobutyl ether; acetophenonessuch as 4-phenoxydichloroacetophenone,2-hydroxy-2-methyl-1-phenylpropan-1-one,1-(4-isopropylphenyl)2-hydroxy-2-methylpropan-1-one,1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxydi-2-methyl-1-propan-1-one,1-hydroxycyclohexyl-phenylketone, 2,2-dimethoxy-1,2-diphenylethan-1-one,2,2-diethoxy-1,2-diphenylethanone,2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropanone-1,4-t-butyldichloroacetophenone, 4-t-butyltrichloroacetophenone,diethoxyacetophenone,2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, and1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime; thioxanthenes suchas thioxanthene, 2-chlorothioxanthene, 2-methylthioxanthene, and2,4-dimethylthioxanthene; alkylanthraquinones such as ethylanthraquinoneand butylanthraquinone; and acylphosphine oxides such as2,4,6-trimethylbenzoyldiphenylphosphine oxide. These photopolymerizationinitiators can be used alone, or two or more kinds of them can be usedin combination.

There can also be used photo acid generating agents such as2,2,2-trichloro-[1-4′-(1,1-dimethylethyl)phenyl]ethanone,2,2-dichloro-1-4′-(phenoxyphenyl)ethanone,α,α,α-tribromomethylphenylsulfone, 2,4,6-tris(trichloromethyl)triazine,2,4-trichloromethyl-(4′-methoxyphenyl)-6-triazine,2,4-trichloromethyl-(4′-methoxystyryl)-6-triazine,2,4-trichloromethyl-(pipronyl)-6-triazine,2,4-trichloromethyl-(4′-methoxynaphthyl)-6-triazine,2[2′(5″-methylfuryl)ethylidene-4,6-bis(trichloromethyl)-S-triazisine,and 2(2′-furyl ethylidene)-4,6-bis(trichloromethyl)-S-triazisine.

If necessary, photosensitizers can be used in combination.

Among these photopolymerization initiators, benzophenones, acetophenonesand acylphosphine oxides are preferred. Specific examples thereofinclude 4,4′-bis(diethylamino)benzophenone, 2-benzyl2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, and2,4,6-trimethylbenzoyldiphenylphosphine oxide.

The amount of the photopolymerization initiator (C) is preferably withina range from 0.1 parts by weight to 20 parts by weight, and morepreferably from 0.2 parts by weight to 10 parts by weight, based on 100parts by weight of the total weight of the photocuring componentcomposed of the photosensitive prepolymer (A-1) and the compound havingan ethylenically unsaturated group (B). When the amount of thephotopolymerization initiator is less than 0.1 parts by weight, curingis sometimes unsatisfactory.

(ii) Electron Beam Curable Resin Material

The electron beam curable resin material used in the first embodimentincludes a positive type one and a negative type one, but may be any oneas long as it can be used as the resist material. Specific examplesthereof include polyvinyl cinnamate, polyvinyl-p-azidebenzoate,polymethyl methacrylate (PMMA), polybutyl methacrylate, methylmethacrylate-methacrylic acid copolymer, methylmethacrylate-acrylonitrile copolymer, methyl methacrylate-isobutylenecopolymer, methyl methacrylate-methyl-a-chloroacrylate copolymer,epoxidated 1,4-polybutadiene (EPB), epoxidated polyisoprene,polyglycidyl methacrylate (PGMA), glycidyl methacrylate-ethyl acrylatecopolymer, glycidyl methacrylate-styrene copolymer, methylvinylsiloxane,polymethylcyclosiloxane (PMCA), polyvinylsiloxane (PVS), copolymerhaving an acrylic group on the side chain, polybutadiene (PB),polydiaryl-o-phthalate (PDOP), copolymer having a methacrylic acid groupand a glycidyl group on the side chain, alkyl ester of alkylvinylether-maleic anhydride copolymer, poly(butene-1-sulfone) (PBS),poly(styrenesulfone), polyvinyl chloride, polystyrene, polyacrylamide,poly-α-methylstyrene, polymethacrylonitrile, cellulose acetate,polyisobutylene, polyvinyl carbazole, polyvinyl ferrocene, polymethylisopropenyl ketone, polymethacrylamide (PMAA), and poly-a-cyanoethylacrylate (PCEA).

(iii) X-Ray Curable Resin Material

Specific examples of the X-ray curable resin material used in the firstembodiment include polymethyl methacrylate (PMMA),poly(butene-1-sulfone) (PBS), polyvinyl ferrocene (PVFc), polybutadiene(PB), polydiaryl-o-phthalate (PDOP), crosslinking electron resist (CER),epoxidated polybutadiene (EPB), and glycidyl methacrylate-ethyl acrylatecopolymer.

(iv) Thermocurable Resin Material

Specific examples of the thermocurable resin material used in the firstembodiment include epoxy resin, phenol resin, silicone resin, melaminederivative (for example, hexamethoxymelamine, hexabutoxylated melamine,or condensed hexamethoxymelamine), urea compound (for example,dimethylol urea), bisphenol A-based compound (for example, tetramethylolbisphenol A), oxazoline compound, and oxetane compound. Thesethermocurable resins can be used alone, or two or more kinds of them canbe used in combination.

Among these thermocurable resins, an epoxy resin is preferred. Specificexamples of the epoxy resin include epoxy compound having two or moreepoxy groups in a molecule, such as bisphenol A type epoxy resin,hydrogenated bisphenol A type epoxy resin, brominated bisphenol A typeepoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin,phenol novolak type epoxy resin, cresol novolak type epoxy resin,N-glycidyl type epoxy resin, novolak type epoxy resin of bisphenol A,chelete type epoxy resin, glyoxal type epoxy resin, aminogroup-containing epoxy resin, rubber modified epoxy resin,dicyclopentadiene phenolic type epoxy resin, silicone modified epoxyresin, or ε-caprolactone modified epoxy resin. Furthermore, bisphenol Stype epoxy resin, diglycidyl phthalate resin, heterocyclic epoxy resin,bixylenol type epoxy resin, biphenyl type epoxy resin andtetraglycidylxylenoylethane resin can be used. These epoxy resins can beused alone, or two or more kinds of them can be used in combination.

II-1. Flame-retarding Agent (D)

The flame-retarding agent (D) as the first embodiment contains at leasta hydrated metal compound (D1) and a brominated epoxy compound (D2) and,if necessary, it can further contain a phosphate ester compound (D3).

(i) Hydrated Metal Compound (D1)

The hydrated metal compound (D1) used in the first embodiment is a metalcompound containing water of crystallization and includes, but is notlimited to, those wherein the amount of bound water is within a rangefrom 12 to 60% (% by weight) per mol as measured by thermal analysis.

In view of the flame-retardant effect, a hydrated metal compound causingendothermy upon thermolysis of 400 J/g or higher, and more preferablyfrom 600 to 2500 J/g is used.

Specific examples of the hydrated metal compound include aluminumhydroxide, magnesium hydroxide, calcium hydroxide, dawsonite, calciumaluminate, dihydated gypsum, zinc borate, barium metaborate,zinchydroxystannate, kaolin, and vermiculite.

Among these hydrated metal compounds, aluminum hydroxide or magnesiumhydroxide is particularly preferred.

As the hydrated metal compound, a hydrotalcite-based compound, which hasa layered crystal structure and also has hydrated anions between crystallayers, is preferably used. As used herein the term “hydrotalcite-basedcompound” is a generic term including hydrotalcite and ahydrotalcite-like compound described hereinafter.

While hydrotalcite is originally a name given to a natural mineralMg₆Al₂(OH)₁₆ CO₃.4–5H₂ O, a lot of minerals having the same crystalstructure were discovered and also synthesized. They are represented bythe following general formulas (a) and (b):[M²⁺ _(1−x)M³⁺ _(x)(OH)₂]^(x+)[A^(n−) _(x/n) .mH₂O]^(x−)  (a)[M³⁺ ₂(OH)₆M¹⁺ _(y)]^(y+)[A^(n−) _(x/n) .mH₂O]^(y−)  (b)wherein 0.1≦x≦0.4, 0<y<2, 0<m, n is a natural number of from 1 to 4, M¹⁺is at least one kind of a monovalent metal such as Li, Na, K, Rb, or Cs,M²⁺ is at least one kind of a divalent metal such as Mg, Ca, Mn, Fe, Co,Ni, Cu, or Zn, M³⁺ is at least one kind of a trivalent metal such as Al,Fe, Cr, or In, A^(n−) is at least one kind of an ion-exchanging anionhaving a valence of n, such as Cl⁻, Br⁻, CO₃ ²⁻, NO₃ ²⁻, SO₄ ²⁻, Fe(CN)₆⁴⁻, tartaric acid ion.

The compound of the general formula (a) wherein M²⁺ is Mg²⁺ and M³⁺ isAl³⁺ is referred to as hydrotalcite, while compounds of the formulas (a)and (b), except the above-mentioned hydrotalcite, are commonly referredto as hydrotalcite-like compounds. It is known that the hydrotalcite andthe hydrotalcite-like compound are different in the structural breaktemperature but are the same in that the structures of these materialscomprise positively charged base layers and interlayers containinganions capable of neutralizing the positive charges and water ofcrystallization, and they have almost the same characteristics. Thesecompounds are described in detail in “Smectite Research SocietyBulletin”, ‘Smectite’ (Vol. 6, No. 1, pp. 12–26, 1996, May).

Specific examples of the hydrotalcite-like compound include stichtite,pyroaurite, reevesite, takovite, honessite, and iowaite.

The particle size of the hydrated metal compound used in the firstembodiment is not specifically limited, but the average particlediameter is preferably 40 μm or less, and more preferably 2 μm or less.When the average particle diameter exceeds 40 μm, the transparency ofthe resist cured film becomes poor and, therefore, the lighttransmittance is lowered and the appearance and smoothness of thesurface of the coating film are sometimes impaired. When using thehydrotalcite-based compound, the size, that is, the average particlediameter of the crystal grain, is preferably 10 μm or less, and morepreferably 5 μm. When the average particle diameter exceeds 10 μm, thelight transmittance of the cured film is lowered and warp is likely tobe caused by shrink anisotropy of the coating in the curing process.

The hydrated metal compound (D1) used in the first embodiment isparticularly preferably surface-treated with a surface treating agenthaving a polarity in view of an improvement in transparency. Examples ofthe surface treating agent having a polarity include silane couplingagent such as epoxysilane, aminosilane, vinylsilane, or mercaptosilane,and titanate coupling agent.

(ii) Brominated Epoxy Compound (D2)

Examples of the brominated epoxy compound (D2) include compoundsrepresented by the following formulas (I) to (III). In the formulas (II)to (III), Y is a hydrogen atom or a group represented by the formula(IV), and Z is a group represented by the formula (IV). p is an integerof 0 or 1 or more, and preferably from 1 to 20, and q is an integer of 0or 1 or more, and preferably from 1 to 10,

Also an acid-modified brominated epoxy resin obtained by reacting thereaction product of the above-described brominated epoxy compound andthe unsaturated group-containing monocarboxylic acid with a saturated orunsaturated group-containing polybasic anhydride can be used. Examplesof the unsaturated group-containing monocarboxylic acid include acrylicacid, dimer of acrylic acid, methacrylic acid, β-furfurylacrylic acid,β-styrylacrylic acid, cinnamic acid, crotonic acid, and α-cyanocinnamicacid. Examples of the saturated or unsaturated group-containingpolybasic anhydride include succinic anhydride, maleic anhydride,tetrahydrophthalic anhydride, phthalic anhydride,methyltetrahydrophthalic anhydride, ethyltetrahydrophthalic anhydride,hexahydrophthalic anhydride, methylhexahydrophthalic anhydride,ethylhexahydrophthalic anhydride, and itaconic anhydride.

Among these brominated epoxy resins, a particularly preferred brominatedepoxy compound is a tetrabromobisphenol A type epoxy resin having anepoxy equivalent of 200 to 3000 and a bromine content of 40 to 60% byweight. When the epoxy equivalent is less than 200, satifactorypliability cannot be obtained. On the other hand, when the epoxyequivalent exceeds 3000, the developability is likely to be lowered andthe availability becomes poor. When the bromine content is less than 50%by weight, satisfactory flame resistance cannot be obtained. On theother hand, when the bromine content exceeds 60% by weight, theavailability becomes poor, sometimes.

As the brominated epoxy compound (D2) as the first embodiment, abrominated epoxy (meth)acrylate compound obtained by reacting theabove-described brominated epoxy compound with the unsaturatedgroup-containing monocarboxylic acid can also be used. As the brominatedepoxy (meth)acrylate compound, for example, tetrabromobisphenol A typeepoxy (meth)acrylate, tetrabromobisphenol F type epoxy (meth)acrylateand tetrabromobisphenol S type epoxy (meth)acrylate are preferredbecause of excellent pliability. The bromine content of this brominatedepoxy (meth)acrylate compound is preferably within a range from 30 to60% by weight. When the bromine content is less than 30% by weight,satisfactory flame resistance cannot be obtained. On the other hand,when the bromine content exceeds 60% by weight, the availability becomespoor, sometimes.

Furthermore, an acid-modified brominated epoxy (meth)acrylate compoundobtained by reacting the above-described brominated epoxy (meth)acrylatecompound with the saturated or unsaturated group-containing polybasicanhydride can also be used.

(iii) Phosphate Ester Compound (D3)

In the first embodiment, as the flame-retarding agent, a phosphate estercompound (D3) can be further included, in addition to theabove-described hydrated metal compound (D1) and the brominated epoxycompound (D2). When the pliability is poor, the pliability can beenhanced by using in combination with the phosphate ester compoundwithout impairing the flame resistance. Therefore, it is preferred. Itbecomes possible to realize balance between the flame resistance and thepliability to a high level by forming a composite flame retardant systemcomposed of three components D1, D2, and D3.

The phosphate ester compound (D3) used optionally in the firstembodiment refers to a compound having a bond of a chemical structurerepresented by the formula: “P—O—R” (R is an organic group) and thosehaving trivalent or pentavalent phosphorus atoms are commonly used.Examples of the compound having trivalent phosphorous atoms includephosphite compound, phosphonite compound, and phosphinite compound.Examples of the compound having pentavalent phosphorous atoms includephosphate compound, phosphonate compound, and phosphinate compound.Among these compounds, a phosphate ester compound having pentavalentphosphorous atoms is preferably used in view of the storage stability.

The organic group, which forms an ester of these phosphate estercompounds, may be any of an aliphatic hydrocarbon group, an aromatichydrocarbon group, and an alicyclic hydrocarbon group. Those havingaromatic hydrocarbon groups, among these organic groups, are preferredin view of the flame resistance and soldering heat resistance.

As the phosphate ester compound, pentavalent compounds having aromatichydrocarbon groups are particularly preferred and examples thereofinclude triphenyl phosphate, resorcinol bis(diphenyl) phosphate,2-ethylhexyldiphenyl phosphate, and those containing a skeletonrepresented by the following formula (V) (in the formula (V), X(s) maybe the same or different and represent a mono- or polyvalent aromaticgroup).

Among these phosphate ester compounds, those containing a skeletonrepresented by the above formula (V) are preferred, and specificexamples thereof include compounds represented by the following formulas(VI) and (VII).

In the formula (VI), R(s) may be the same or different and represent ahydrogen atom or an alkyl group having 1 to 5 carbon atoms. Y representsa direct bond, an alkylene group, a phenylene group, —S—, —SO₂—, or—CO—. Ar(s) may be the same or different and represent an aromaticgroup, or an aromatic group substituted with an organic group. k and meach represents an integer of 0 or more and 2 or less, k+m is an integerof 0 or more and 2 or less, and n is an integer of 0 or more.

The molecular weight of the phosphate ester compound (D3) is 300 ormore, preferably 350 or more, and more preferably 500 or more. It ismore preferred in view of the moisture resistance and the soldering heatresistance that the phosphate ester compound having a molecular weightof 300 or more account for 50% by weight or more of the entire phosphateester compound. In the composition as the first embodiment, the sameeffect can be obtained by incorporating a phosphate ester havingtrivalent phosphorus atoms into the composition and converting it into aphosphate ester having pentavalent phosphorus atoms by means ofoxidation in the composition.

(iv) Amount of Flame-retarding Agent

The amount of D1, D2, and D3, which is optionally used, in theflame-retarding agent used in the first embodiment is not specificallylimited. In the case of the resist curable resin material (photocurableresin material), the amount of D1 is preferably within a range from 10to 100 parts by weight, the amount of D2 is preferably within a rangefrom 10 to 80 parts by weight, and the amount of D3 is preferably withina range from 0.5 to 40 parts by weight, when optionally used, based on100 parts by weight of the total weight of the components (A-1), (B) and(C). More preferably, the amount of D1 is within a range from 20 to 80parts by weight, the amount of D2 is within a range from 20 to 60 partsby weight, and the amount of D3 is preferably within a range from 1 to30 parts by weight, when optionally used. Particularly preferably, theamount of D1 is within a range from 30 to 60 parts by weight, the amountof D2 is within a range from 30 to 50 parts by weight, and the amount ofD3 is preferably within a range from 5 to 20 parts by weight, whenoptionally used.

Based on the amount described above, the amount of D1 to D3 based on thetotal amount of the flame-retarding agent and the resist curable resincomposition is shown below.

The amount of the hydrated metal compound (D1) is not specificallylimited, but is preferably within a range from 11 to 91% by weight, morepreferably from 25 to 80% by weight, and particularly preferably from 38to 67% by weight, based on the total amount of the flame-retarding agentwhen the flame-retarding agent (D) is composed of the hydrated metalcompound (D1) and the brominated epoxy compound (D2). Also the amount ofthe hydrated metal compound (D1) relative to the total amount of theresist curable resin composition as the first embodiment is notspecifically limited, but is preferably within a range from 5 to 48% byweight, more preferably from 11 to 40% by weight, and particularlypreferably from 16 to 32% by weight.

When the flame-retarding agent is composed of the hydrated metalcompound (D1), the brominated epoxy compound (D2) and the phosphateester compound (D3), the amount of the hydrated metal compound (D1) ispreferably within a range from 7 to 90% by weight, more preferably from18 to 79% by weight, and particularly preferably from 30 to 63% byweight, based on the total amount of the flame-retarding agent. Also theamount is preferably within a range from 4 to 47% by weight, morepreferably from 9 to 40% by weight, and particularly preferably from 15to 31% by weight, based on the total amount of the resist curable resincomposition as the first embodiment.

When the amount of the hydrated metal compound is too small, the flameresistance is poor. As a result, the amount of the brominated epoxycompound and/or the phosphate ester compound must be increase, therebylowering the acid value and the developability. On the other hand, whenthe amount is too large, the cured film is liable to become opaque andthe flexibility is lowered, thereby causing poor pliability. Also warpoccurs sometimes.

The amount of the brominated epoxy compound (D2) is not specificallylimited, but is preferably within a range from 9 to 89% by weight, morepreferably from 20 to 75% by weight, and particularly preferably from 33to 63% by weight, based on the total amount of the flame-retarding agentwhen the flame-retarding agent is composed of the hydrated metalcompound (D1) and the brominated epoxy compound (D2). Also thebrominated epoxy compound (D2) relative to the total amount of theresist curable resin composition as the first embodiment is notspecifically limited, but is preferably within a range from 5 to 42% byweight, more preferably from 10 to 33% by weight, and particularlypreferably from 15 to 28% by weight.

When the flame-retarding agent is composed of the hydrated metalcompound (D1), the brominated epoxy compound (D2) and the phosphateester compound (D3), the amount of the brominated epoxy compound (D2) ispreferably within a range from 6 to 88% by weight, more preferably from15 to 74% by weight, and particularly preferably from 27 to 59% byweight, based on the total amount of the flame-retarding agent. Also theamount is preferably within a range from 4 to 42% by weight, preferablyfrom 9 to 33% by weight, and particularly preferably from 14 to 27% byweight, based on the total amount of the resist curable resincomposition as the first embodiment. When the amount of the brominatedepoxy compound is too small, the flame-retarding effect is sometimespoor. On the other hand, when the amount is too large, the pliabilityand the developability are sometimes lowered.

When using the phosphate ester compound (D3), the amount is notspecifically limited, but is preferably within a range from 0.2 to 67%by weight, more preferably from 0.7 to 43% by weight, and particularlypreferably from 4 to 25% by weight, based on the total amount of theflame-retarding agent. Also the amount of the phosphate ester compoundrelative to the total amount of the resist curable resin composition asthe first embodiment is not specifically limited, but is preferablywithin a range from 0.1 to 25% by weight, preferably from 0.4 to 18% byweight, and particularly preferably from 2 to 12% by weight. When theamount of the phosphate ester compound (D3) is too small, the pliabilityis sometimes poor. On the other hand, when the amount is too large, theappearance of the coating film is impaired by bleedout.

The total amount of the flame-retarding agent in the resist curableresin composition as the first embodiment is preferably within a rangefrom 17 to 69% by weight, more preferably from 29 to 63% by weight, andparticularly preferably from 39 to 57% by weight. When the amount of theflame-retarding agent is too small, the flame resistance is poor. On theother hand, when the amount is too large, the transparency, pliability,strength (folding resistance) and developability are sometimes lowered.

III-1. Other Components

(i) Thermocurable Resin (E)

In the first embodiment, when the resist curable resin material is aphotocurable resin material, an electron beam curable resin material, oran X-ray curable resin material, the resist curable resin compositioncan optionally contain a thermocurable resin (E) as a thermocuringcomponent. Such a thermocurable resin (E) may be a resin which isself-cured by heat, or a resin which reacts with carboxyl group of thephotosensitive prepolymer by heat. Such a thermocurable resin (E) can beselected from the same resin materials as those used in thethermocurable resin material described above. These thermocurable resinscan be used alone, or two or more kinds of them can be used incombination. Among these thermocurable resins, an epoxy resin ispreferred. Specific examples of the epoxy resin can also be selectedfrom those used in the thermocurable resin material described above.

The resist curable resin composition as the first embodiment ispreferably a nonuniform system containing a phase made of the epoxyresin. Specifically, it is in the state where a solid or semi-solidepoxy resin is recognized in the resist curable resin composition beforecuring and the epoxy resin is mixed nonuniformly in the resist curableresin composition. The particle diameter is preferably a particlediameter which exerts an adverse influence on the screen printing andproduction of the dry film. For example, there is also included thestate where the entire resist curable resin composition before curing isnot uniformly transparent and at least a portion of the composition isopaque. It is preferred that the resist curable resin composition beforecuring is be a nonuniform system containing a phase made of the epoxyresin, as described above, because the shelf life of the resist curableresin composition is prolonged.

Examples of preferred epoxy resin used for these purposes includebisphenol S type epoxy resin, diglycidyl phthalate resin, heterocyclicepoxy resin, bixylenol type epoxy resin, biphenyl type epoxy resin, andtetraglycidyl xylenoylethane resin. More preferably, the resist curableresin composition contains a phase made of the epoxy resin and theresist curable resin composition before curing is a nonuniform system.As the epoxy resin wherein the resist curable resin composition beforecuring is a nonuniform system, a biphenyl type epoxy resin is morepreferred because it is a crystal having a clear melting point andeasily forms a nonuniform composition and can produce a cured articlehaving high heat resistance.

In the resist curable resin composition as the first embodiment, whenusing in combination with the thermocurable resin (E), the amount ispreferably within a range from 10 to 150 parts by weight, and morepreferably from 10 to 50 parts by weight, based on 100 parts by weightof the total weight of the curing component (the photosensitiveprepolymer (A-1) and the compound having an ethylenically unsaturatedgroup (B)) when using the photocurable resin material.

When the amount of thermocurable resin (E) is less than 10 parts byweight, the soldering heat resistance of the cured film becomesunsatisfactory, sometimes. On the other hand, when the amount exceeds150 parts by weight, the shrink amount of the cured film increases.Therefore, when using the cured film as an insulating protective film ofa FPC board, warp (curl) tends to increase.

(ii) Thermal Polymerization Catalyst (F)

In the first embodiment, when using the photocurable resin material (orelectron beam curable resin material or X-ray curable resin material) incombination with the thermocurable resin (E), a thermal polymerizationcatalyst (F) having an action of thermocuring the thermocurable resin(E) can be optionally used. Specifically, there can be used amines;amine salts or quaternary ammonium salts such as chloride of amines;acid anhydrides such as cyclic aliphatic acid anhydride, aliphatic acidanhydride, and aromatic acid anhydride; polyamides; imidazoles;nitrogen-containing heterocyclic compounds such as triazine compound;and organometallic compounds. These thermal polymerization catalysts canbe used alone, or two or more kinds of them can be used in combination.

Examples of amines include aliphatic and aromatic primary, secondary,and tertiary amines. Examples of the aliphatic amine includepolymethylenediamine, polyetherdiamine, diethylenetriamine,triethylenetriamine, tetraethylenepentamine, triethylenetetramine,dimethylaminopropylamine, menthenediamine, aminoethylethanolamine,bis(hexamethylene)triamine, 1,3,6-trisaminomethylhexane, tributylamine,1,4-diazabicyclo[2,2,2]octane, and 1,8-diazabicyclo[5,4,0]undecen-7-ene.Examples of the aromatic amine include methaphenylenediamine,diaminodiphenylmethane, diaminodiphenylmethane, anddiaminodiphenylsulfone.

Examples of acid anhydrides include aromatic acid anhydride such asphthalic anhydride, trimellitic anhydride, benzophenonetetracarboxylicahhydride, ethylene glycol bis(anhydro trimellitate), or glyceroltris(anhydro trimellitate), maleic anhydride, succinic anhydride,methylnadic anhydride, hexahydrophthalic anhydride, tetrahydrophthalicanhydride, polyadipic anhydride, chlorendic anhydride, andtetrabromophthalic anhydride.

Examples of polyamides include polyaminoamide having first and secondamino groups obtained by reacting dimer acid with polyamine such asdiethylenetriamine or triethylenetetramine.

Specific examples of the imidazoles include imidazole,2-ethyl-4-methylimidazole, N-benzyl-2-methylimidazole,1-cyanoethyl-2-undecylimidazolium trimellitate, and 2-methylimidazoliumisocyanurate.

The triazine compound is a compound having a six-membered ringcontaining three nitrogen atoms, and examples thereof include melaminecompound, cyanuric acid compound, and cyanuric acid melamine compound.Specific examples of the melamine compound include melamine,N-ethylenemelamine, and N,N′,N″-triphenylmelamine. Examples of thecyanuric acid compound include cyanuric acid, isocyanuric acid,trimethyl cyanurate, trismethyl isocyanurate, triethyl cyanurate,trisethyl isocyanurate, tri(n-propyl) cyanurate, tris(n-propyl)isocyanurate, diethyl cyanurate, N,N′-diethyl isocyanurate, methylcyanurate, and methyl isocyanurate. Examples of the cyanuric acidmelamine compound include an equimolar reaction product of a melaminecompound and a cyanuric acid compound.

Examples of the organometallic compound include organic acid metal salt,1,3-diketone metal complex salt, and metal alkoxide. Specific examplesthereof include organic acid metal salt such as dibutyltin dilaurate,dibutyltin maleate, or zinc 2-ethylhexanoate; 1,3-diketone metal complexsalt such as nickel acetylacetonate or zinc acetylacetonate; and metalalkoxide such as titanium tetrabutoxide, zirconium tetrabutoxide, oraluminum butoxide.

The amount of the thermal polymerization catalyst (F) is preferablywithin a range from 0.5 to 20 parts by weight, and more preferably from1 to 10 parts by weight, based on 100 parts by weight of thethermocurable resin (E). When the amount of the thermal polymerizationcatalyst (F) is less than 0.5 parts by weight, the curing reaction doesnot proceed satisfactorily and the heat resistance is lowered. Sincecuring at high temperature for a long time is required, the operationefficiency is sometimes lowered. On the other hand, when the amount ismore than 20 parts by weight, the catalyst reacts with carboxyl groupsin the resist curable resin composition and gelation is liable to occur,thus causing a problem such as lowering of the storage stability.

(iii) Others

If necessary, organic solvents may be added to the resist curable resincomposition to control the viscosity. Control of the viscosity makes iteasy to apply or print on the objective article using a roller coating,spin coating, screen coating, curtain coating, knife coating or bladecoating method.

Examples of the organic solvent include ketone solvent such as ethylmethyl ketone, methyl isobutyl ketone, or cyclohexanone; ester solventsuch as ethyl acetoacetate, y-butyrolactone, or butyl acetate; alcoholsolvent such as butanol or benzyl alcohol; cellosolve solvent, carbitolsolvent, or ester or ether derivative thereof, such as carbitol acetateor methyl cellosolve acetate; amide solvent such asN,N-dimethylformamide, N,N-dimethylacetamide, or N-methyl-2-pyrrolidone;dimethyl sulfoxide; phenol solvent such as phenol or cresol; nitrocompound solvent; toluene, xylene, hexamethylbenzene, and cumenearomatic solvent; and aromatic and alicyclic solvent made of hydrocarbonsuch as tetralin, decalin, or dipentene. These organic solvents can beused alone, or two or more kinds of them can be used in combination.

The amount of the organic solvent is preferably controlled so that theviscosity of the resist curable resin composition is set within a rangefrom 500 to 500,000 mPa·s [as measured at 25° C. using a B typeviscometer (Brookfield Viscometer)]. More preferably, the viscosity iswithin a range from 1,000 to 500,000 mPa·s. Such a viscosity is suitedfor coating or printing onto the objective article, resulting in goodhandling. The amount of the organic solvent suited to achieve such aviscosity is 1.5 times by weight, as much as the solid content otherthan the organic solvent. When the amount exceeds 1.5 times by weight,the solid content is reduced and, when printing this resist curableresin composition on the substrate, satisfactory film thickness cannotbe obtained by a single printing operation and printing must beconducted several times.

Such a resist curable resin composition can also be used as ink byfurther adding colorants. Examples of the colorant includephthalocyanine blue, phthalocyanine green, iodine green, disazo yellow,crystal violet, titanium oxide, carbon black, and naphthalene black.When used as the ink, the viscosity is preferably within a range from500 to 500,000 mPa·s [as measured at 25° C. using a B type viscometer(Brookfield Viscometer)].

To the resist curable resin composition as the first embodiment, flowmodifiers can be added to control the fluidity. The flow modifier ispreferred because it can appropriately control the fluidity of theresist curable resin composition when the resist curable resincomposition is applied onto the objective article using a rollercoating, spin coating, screen coating, curtain coating, knife coating orblade coating method. Examples of the flow modifier include inorganicand organic fillers, waxes, and surfactants.

Specific examples of the inorganic filler include talc, barium sulfate,barium titanate, silica, alumina, clay, magnesium carbonate, calciumcarbonate, aluminum hydroxide, and silicate compound. Specific examplesof the organic filler include silicone resin, silicone rubber, andfluororesin. Specific examples of the wax include polyamide wax andpolyethylene oxide wax. Specific examples of the surfactant includesilicone oil, higher fatty acid ester, and amide. These flow modifierscan be used alone, or two or more kinds of them can be used incombination. Among these flow modifiers, the inorganic filler ispreferably used because not only the fluidity but also properties suchas adhesion and hardness of the resist curable resin composition can beimproved.

If necessary, additives such as thermal polymerization inhibitors,thickeners, defoamers, leveling agents, and adhesion imparting agent canbe added to the resist curable resin composition.

Examples of the thermal polymerization inhibitor include hydroquinone,hydroquinone monomethyl ether, tert-butyl catechol, pyrogallol, andphenothiazine.

Examples of the thickener include layered silicates such as hectorite,montmorillonite, saponite, beidellite, stivensite, mica terasilicate, orteniolite, and interlaminar compound obtained by treating the layeredsilicate with organic cations, silica, and organized silica.

The defoamer is used to remove bubbles formed during printing, coatingand curing, and specific examples thereof include acrylic- andsilicon-based surfactants.

The leveling agent is used to remove the unevenness of the surface ofthe coating film formed during the printing and coating, and specificexamples thereof include acrylic- and silicon-based surfactants.

Examples of the adhesion imparting agent include imidazole-based,thiazole-based, triazole-based and silane coupling agents.

As other additives, ultraviolet inhibitors and plasticizers can be addedto secure the storage stability as long as the object of this embodimentis not impaired.

The resist curable resin composition as the second embodiment of thepresent invention will be described below. The resist curable resincomposition as the second embodiment comprises a resist curable resinmaterial and a hydrated metal compound. With respect to the sameconstitution as in the first embodiment, description is omitted.

I-2. Resist Curable Resin Composition

(i) Photocurable Resin Material

(1) Photosensitive Prepolymer (A-2)

<Urethane (Meth)Acrylate Compound Having a Carboxyl Group (UA)>

When using a urethane (meth)acrylate compounds (a) and a urethane(meth)acrylate compound (b), which differ in acid value, in combination,a weight ratio of the urethane (meth)acrylate compound (a) to theurethane (meth)acrylate compound (b) is preferably 40–90:60–10, andpreferably 50–80:50–20, in the total amount (100 parts by weight) of theurethane (meth)acrylate compound having a carboxyl group.

Others are the same as in the first embodiment.

(2) Compound Having an Ethylenically Unsaturated Group (B)

Compound (B) of the second embodiment is the same as the compound havingan ethylenically unsaturated group (B) of the first embodiment.

(3) Photopolymerization Initiator (C)

Photopolymerization initiator (C) of the second embodiment is the sameas the photopolymerization initiator (C) of the first embodiment.

(ii) Electron Beam Curable Resin Material

Electron beam curable resin materials of the second embodiment are thesame as the the electron beam curable resin materials of the firstembodiment.

(iii) X-Ray Curable Resin Material

X-ray curable resin materials of the second embodiment are the same asthe X-ray curable resin materials of the first embodiment.

(iv) Thermocurable Resin Material

Thermocurable resin materials of the second embodiment are the same asthe thermocurable resin materials of the first embodiment.

II-2. Surface-Treated Hydrated Metal Compound

In the second embodiment, a surface-treated hydrated metal compound isincorporated into the resist curable resin material described above.

(i) Hydrated Metal Compound

The hydrated metal compound used in the second embodiment is a metalcompound containing water of crystallization and includes, but is notlimited to, those causing endothermy upon thermolysis of 400 J/g orhigher.

Specific examples of the hydrated metal compound are the same as thosedescribed in the first embodiment.

As the hydrated metal compound, a hydrotalcite-based compound, which hasa layered crystal structure and also has hydrated anions between crystallayers, or a hydrotalcite-based compound, which has a layered crystalstructure and also has organic anions between crystal layers ispreferably used. Hydrotalcites as the second embodiment are representedby the following general formulas (c) and (d):[M²⁺ _(1−x)M³⁺ _(x)(OH)₂]^(x+)[anion]^(x−)  (c)[M³⁺ ₂(OH)₆M¹⁺ _(y)]^(y+)[anion]^(y−)  (d)wherein 0.1≦x≦0.4, 0<y<2, M¹⁺ is at least one kind of a monovalent metalsuch as Li, Na, K, Rb, or Cs, M²⁺ is at least one kind of a divalentmetal such as Mg, Ca, Mn, Fe, Co, Ni, Cu, or Zn, M³⁺ is at least onekind of a trivalent metal such as Al, Fe, Cr, or In, and each[anion]^(x−) and [anion]^(y−) is a hydrated anion or an organic anion,which exists between crystal layers.

Similarly to the first embodiment, the compound of the general formula(c) wherein M²⁺ is Mg²⁺ and M³⁺ is Al³⁺ is referred to as hydrotalcite,while compounds of the formulas (c) and (d), except the above-mentionedhydrotalcite, are commonly referred to as hydrotalcite-like compounds.

In the case of the hydrotalcite-based compound having hydrated anionsbetween the crystal layers, [anion]^(x−) and [anion]^(y−) are convertedinto a hydrated anion represented by [A^(n−) _(x/n).mH₂O]^(x−) and[A^(n−) _(x/n).mH₂O]^(y−) respectively in the above general formulas (c)and (d). Therefore, the hydrotalcite-based compounds having hydratedanions between the crystal layers are represented by the followinggeneral formulas (e) and (f). In the formulas, A^(n−) is at least onekind of an ion-exchanging anion having a valence of n, such as Cl⁻, Br⁻,CO₃ ²⁻, NO₃ ²⁻, SO₄ ²⁻, Fe(CN)₆ ⁴⁻, and tartaric acid ion.[M²⁺ _(1−x)M³⁺ _(x)(OH)₂]^(x+)[A^(n−) _(x/n) .mH₂O]^(x−)  (e)[M³⁺ ₂(OH)₆M¹⁺ _(y)]^(y+)[A^(n−) _(x/n) .mH₂O]^(y−)  (f)

In the formulas, 0.1≦x≦0.4, 0<y<2, m is an integer of 1 or more, and nis an integer of from 1 to 4. M¹⁺, M²⁺, and M³⁺ are as defined in theformulas (c) and (d).

In the case of the hydrotalcite-based compound having organic anionsbetween the crystal layers, the organic anions are not specificallylimited, but are preferably amino acids, sulfur-containing compounds,nitrogen-containing heterocyclic compounds, and salt compounds thereof.

Specific examples thereof include amino acid derivatives such asleucine, cysteine, phenylalanine, tyrosine, aspartic acid, glutaminicacid, lysine, 6-aminohexylcarboxylic acid, 12-aminolaurylcarboxylicacid, N,N-dimethyl-6-aminohexylcarboxylic acid,N-n-dodecyl-N,N-dimethyl-10-aminodecylcarboxylic acid, ordimethyl-N-12-aminolaurylcarboxylic acid; sulfur-containing compoundsand salt compounds thereof, such as 2-chlorobenzothiazole, thioaceticacid, methyldithiocarbamic acid, or dimethyldithianocarbamic acid; andnitrogen-containing heterocyclic compounds and salt compounds thereof,such as 2-mercaptothiazoline, 2,5-dimercapto-1,3,4-thiadiazole,1-carboxymethyl-5-mercapto-1H-tetrazole, or2,4,6-trimercapto-s-triazine.

The hydrotalcite-based compound having organic anions between thecrystal layers does not exist in nature and can be obtained by treatingthe hydrotalcite-based compound with an organic solvent containingpredetermined organic anions.

The particle size of the surface-treated hydrated metal compound used inthe second embodiment is not specifically limited, but the averageparticle diameter is preferably within a range from 0.05 to 40 μm, andmore preferably from 0.1 to 2.0 μm. When the average particle diameterexceeds 30 μm, the transparency of the cured film becomes poor, andtherefore, the light transmittance is lowered and the appearance and thesmoothness of the surface of the coating film are impaired, sometimes.When the average particle diameter is less than 0.05 μm, there is such adrawback that the productivity of the powder is drastically lowered.

When using the hydrotalcite-based compound, the particle size, that is,the average particle diameter is within a range from 0.05 to 10 μm, andmore preferably from 0.1 to 5.0 μm. When the average particle diameterexceeds 10 μm, the light transmittance of the cured film is lowered andwarp is likely to be caused by shrink anisotropy of the coating in thecuring process. On the other hand, when the average particle diameter isless than 0.05 μm, there is a drawback in that the productivity of thepowder is drastically lowered.

The particle diameter of the surface-treated hydrated metal compound asthe second embodiment can be determined by the sedimentation typeparticle size measuring method in a solvent or the light scatteringmethod. Alternatively, the particle diameter may be determined from afrequency distribution of each fraction based on the number as areference, or accumulation distribution after directing observingparticles using a transmission electron microscope or a scanningelectron microscope and determining a geometrical diameter of individualparticle. The value of the average particle diameter varies depending onthe measuring method. The average particle diameter due to observationusing the above microcope is a value obtained from logarithmic normaldistribution after determining an average value of a major axis andaminor axis of an individual particle. In this embodiment, the valueobtained by any method described above may be within a range of theabove average particle diameter.

The hydrated metal compound used in the second embodiment is preferablya hydrated metal causing the endothermy upon thermolysis of 400 J/g orhigher, and more preferably 600 to 2,500 J/g. When the endothermy is 400J/g or higher, a high flame-retarding effect is obtained, sometimes.

(ii) Surface Treating Agent

A surface treating agent can be used in the surface treatment of thehydrated metal compound as the second embodiment. By mixing thesurface-treated hydrated metal compound with the curable resin material,an increase in viscosity is suppressed, thereby to easily form a highconcentration masterbatch intermediate material, and the transparency isnoticeably improved. Since the dispersion state of the hydrated metalcompound particles in the curable resin composition is improved, thepliability and the flame resistance are remarkably improved.

The surface treating agent is not specifically limited, but those havingan amphipathic property and a polarity are preferred.

Specific examples of the surface treating agent having an amphipathicproperty include those selected from the group consisting of saturatedand unsaturated fatty acids having 8 or more carbon atoms; primaryamine, secondary amine, tertiary amine, and a chloride thereof;quaternary ammonium salt; amine compound; and amino acid derivative.

More specific examples thereof include primary amine such as octylamine,laurylamine, tetradecylamine, hexadecylamine, stearylamine, oleylamine,acrylamine, benzylamine, or aniline; secondary amine such asdilaurylamine, ditetradecylamine, dihexadecylamine, distearylamine, orN-methylaniline; tertiary amine such as dimethyloctylamine,dimethyldecylamine, dimethyllaurylamine, dimethylmyristylamine,dimethylpalmitylamine, dimethylstearylamine, dilaurylmonomethylamine,tributylamine, trioctylamine, or N,N-dimethylaniline; and quaternaryammonium such as tetrabutyl ammonium ion, tetrahexyl ammonium ion,dihexyldimethyl ammonium ion, dioctyldimethyl ammonium ion,hexatrimethyl ammonium ion, octatrimethyl ammonium ion, dodecyltrimethylammonium ion, hexadecyltrimethyl ammonium ion, stearyltrimethyl ammoniumion, docosenyltrimethyl ammonium ion, cetyltrimethyl ammonium ion,cetyltriethyl ammonium ion, hexadecyl ammonium ion,tetradecyldimethylbenzyl ammonium ion, stearyldimethylbenzyl ammoniumion, dioleyldimethyl ammonium ion, N-methyldiethanol lauryl ammoniumion, dipropanolmonomethyl lauryl ammonium ion, dimethylmonoethanollauryl ammonium ion, polyoxyetylenedodecylmonomethyl ammonium ion, oralkylaminopropylamine quaternized compound.

It further includes saturated fatty acid and metal salt thereof, such ascaproic acid, lauric acid, myristic acid, palmitic acid, stearic acid,or arachic acid; unsaturated fatty acid and metal salt thereof, such asundecylenic acid, cetoleic acid, erucic acid, brassidic acid, sorbicacid, oleic acid, linoleic acid, or arachidonic acid; and amino acidderivatives such as leucine, phenylalanine, tyrosine, lysine,12-aminolaurylcarboxylic acid,N-n-dodecyl-N,N-dimethyl-10-aminodecylcarboxylic acid, ordimethyl-N-12-aminolaurylcarboxylic acid.

Specific examples of the surface treating agent having a polarityinclude those selected from the group consisting of titanate couplingagent, aluminum coupling agent, zircoaluminate coupling agent, andsilane coupling agent.

Examples of the silane coupling agent include3-chloropropyltrimethoxysilane, vinyltrichlorosilane,vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-methacryloxypropyltrimethoxysilane,2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,3-glycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane,3-aminopropyltriethoxysilane,N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and3-ureidopropyltriethoxysilane.

Examples of the titanate coupling agent include isopropyltriisostearoyltitanate, isopropyltridodecylbenzenesulfonyl titanate,isopropyltris(dioctylpyrophosphate) titanate,tetraisopropylbis(dioctylphosphite) titanate,tetraoctylbis(ditridecylphosphite) titanate,tetra(2,2-diallyloxymethyl-1-butyl)bis(di-tridecyl)phosphite titanate,bis(dioctylpyrophosphate)oxyacetate titanate,bis(dioctylpyrophosphate)ethylene titanate, isopropyltrioctanoyltitanate, isopropyldimethacrylisostearoyl titanate,isopropylisostearoyldiacryl titanate, isopropyltri(dioctylphosphate)titanate, isopropylcumylphenyl titanate,isopropyltri(N-amidoethyl-aminoethyl) titanate, dicumylphenyloxyacetatetitanate, and diisostearoylethylene titanate.

Examples of the aluminum coupling agent include acetoalkoxy aluminumdiisopropylate.

Examples of the zircoaluminate coupling agent include compounds having askeleton represented by the following general formula. In the functionalgroup (—RX), R represents an optionally substituted alkylene group, andX represents an amino group, a carboxyl group, a mercapto group, analkyl group or an alkenyl group. RX— includes the group of the followingorganic groups. These compounds may have one or two or more kinds ofthese functional groups.

Group of organic groups; —(CH₂)₂NH₂, —(CH₂)₄COOH, —(CH₂)₁₂CH₃,—C(CH₃)═CH₂, —(CH₂)₂SH, —(CH₂)₂NH₂

The amount of the surface treating agent is preferably within a rangefrom about 0.1 to 5.0% by weight, and more preferably from about 0.4 to2.0% by weight, based on the amount of the hydrated metal compound. Whenthe amount of the surface treating agent is too small, the formabilityis sometimes poor because an increase in viscosity is likely to occurwhen formed into a film-like article such as cured film. On the otherhand, when the amount of the surface treating agent is too large, theheat resistance is lowered by an increase in unreacted product andoutgassing occurs in the heating step.

When using the hydrotalcite-based compound having organic anions duringthe crystal layers, it is surface-treated after treating with a solventcontaining organic anions. Since the hydrotalcite-based compound havingorganic anions during the crystal layers itself is an alreadysurface-treated substance, it is not necessary to surface-treat with theabove surface treating agent and the compound can be used as it is as a“hydrated metal compound surface-treated with the surface treatingagent” as the second embodiment.

(iii) Amount

The surface-treated hydrated metal compound as the second embodiment ispreferably incorporated in the amount within a range from 10 to 100parts by weight, more preferably from 20 to 80 parts by weight, andparticularly preferably from 30 to 60 parts by weight, based on 100parts by weight of the resist curable resin material.

When the amount of the hydrated metal compound is too small, the flameresistance is poor and, therefore, the amount of the otherflame-retarding components such as brominated epoxy compound andphosphate ester compound must be increased so as to obtain a highflame-retarding effect. Consequently, the acid value of the solidcontent and the developability are lowered. On the other hand, when theamount is too large, the resulting cured film is likely to become opaqueand the flexibility is lowered, thereby lowering the pliability. Also,warping sometimes occurs.

III-2. Other Components

If necessary, various compounds can be incorporated into the resistcurable resin composition of the present invention, in addition to thecurable prepolymers and hydrated metal compounds described above. Forexample, the brominated epoxy compound and/or the phosphate estercompound can be incorporated as the flame-retarding component. Anexcellent flame-retarding effect is exerted by using in combination withthe hydrated metal compound described above.

When the resist curable resin material is a photocurable resin material,an electron beam curable resin material or a X-ray curable resinmaterial, the resist curable resin composition can optionally contain athermocurable resin, as a thermocuring component, together with athermal polymerization catalyst.

(i) Brominated Epoxy Compound

The amount of the brominated epoxy compound to be incorporated into theresist curable resin composition is not specifically limited, but ispreferably within a range from 10 to 80 parts by weight, more preferablyfrom 20 to 60 parts by weight, and particularly preferably from 30 to 50parts by weight, based on 100 parts by weight the resist curable resincomposition. When the amount of the brominated epoxy compound is toosmall, the flame-retarding effect is sometimes poor. On the other hand,when the amount is too large, the pliability and developability aresometimes lowered.

Others are the same as in the first embodiment.

(ii) Phosphate Ester Compound

If necessary, a phosphate ester compound can be incorporated.Consequently, the flame resistance of the curable resin composition canbe enhanced. When the pliability is poor, the pliability can be enhancedby using the hydrated metal compound, the brominated epoxy compound, andthe phosphate ester compound in combination without impairing the flameresistance. Therefore, it is preferred. It becomes possible to realizebalance between the flame resistance and the pliability to a high levelby forming a composite flame retardant system composed of threecomponents of the hydrated metal compound, the brominated epoxycompound, and the phosphate ester compound.

These phosphate ester compounds may be used alone, or several kinds ofthem may be used in combination.

The amount of the phosphate ester compound is not specifically limited,but is preferably within a range from 0.5 to 40 parts by weight, morepreferably from 1 to 30 parts by weight, and particularly from 5 to 20parts by weight, based on 100 parts by weight of the resist curableresin composition. When the amount of the phosphate ester compound istoo small, the pliability is sometimes poor. On the other hand, when theamount is too large, the appearance of the coating film is sometimesimpaired by bleedout.

Others are as the same as in the first embodiment.

(iii) Thermocurable Resin (E)

Thermocurable resin (E) of the second embodiment is the same as thethermocurable resin (E) of the first embodiment.

(iv) Thermal Polymerization Catalyst (F)

Thermal polymerization catalyst (F) of the second embodiment is the sameas the thermal polymerization catalyst (F) of the first embodiment.

(v) Others

Others are the same as in the first embodiment.

The method for preparing a resist curable resin composition will bedescribed below.

The resist curable resin compositions as the first and secondembodiments of the present invention can be prepared by mixing the aboverespective components using a conventional method. The mixing method isnot specifically limited and the remaining components may be mixed aftermixing a portion of component, or all components may be mixed at a time.

Specifically, the above respective components are preferably mixed andare subsequently melt-kneaded. For example, the resist curable resincomposition is prepared by melt-kneading using a known kneading meanssuch as a Banbury mixer, kneader, roller, single-screw extruder,twin-screw extruder, or co-kneader. The melt temperature is preferablywithin a range from 60 to 130° C. A resist curable resin composition,wherein the viscosity at room temperature is reduced to that of ink bydiluting with a solvent, can be prepared by a known kneading means suchas a three roll mill or a beads mill.

The cured resin and use of the resist curable resin composition will bedescribed below.

The resist curable resin compositions as the first and secondembodiments of the present invention can be converted into a curedarticle by applying on a substrate in a proper thickness, heat-treatingand drying the coating film, following by exposure, development, andfurther thermocuring.

The resist curable resin composition of the present invention can beused for various purposes, and is in particularly suited for use as aninsulating protective coating film of a print circuit board because itis superior in photosensitivity and developability and is also superiorin adhesion to the substrate, insulating properties, heat resistance,warp resistance, pliability and appearance when cured to form a thinfilm.

The insualting protective coating film is formed by applying a resistcurable resin composition or ink on a substrate with a circuit formed bya conductor in a thickness of 10 to 100 μm, drying while heat-treatingat a temperature within a range from 60 to 100° C. for about 5 to 30minutes, thereby reducing to the thickness to 5 to 70 μm, exposing tolight through a nagative mask with a desired exposure pattern,developing while removing the non-exposure portion with a developingsolution, and thermocuring at a temperature within a range from 100 to180° C. for about 10 to 40 minutes. This resist curable resincomposition is superior in flame resistance and is particularly superiorin pliability and flexibility when converted into the cured article.Therefore, the resist curable resin composition is particularly suitedfor use as an insulating protective coating film of an FPC board, thusmaking it possible to produce an FPC board which is less likely to causecurling and is also superior in handling property.

For example, the resist curable resin composition may be used as aninsulating resin layer between multi-layered print circuit boards.

Active light used in exposure may be active light emitted from a knownactive light source such as carbon arc, mercury vapor arc, or xenon arc.Since the sensitivity of the photopolymerization initiator (C) containedin the photosensitive layer is usually maximum in the ultraviolet range,the activating light source is preferably an activating light sourcewhich effectively emits ultraviolet light. As a matter of course, whenthe photopolymerization initiator (C) are sensitive to visible light,for example, 9,10-phenanthrenequinone, visible light may be used asactivating rays. As the light source, a photographic photoflood lamp anda solar lamp are used, in addition to the active light sources describedabove.

As the developing solution, an aqueous alkali solution such as potassiumhydroxide, sodium hydroxide, sodium carbonate, potassium carbonate,sodium phosphate, sodium silicate, ammonia, or amines can be used.

The resist curable resin composition can also be used as aphotosensitive layer of a photosensitive dry film. The photosensitivedry film comprises a base made of a polymer film and a photosensitivelayer made of the resist curable resin composition formed on the base.The thickness of the photosensitive layer is preferably within a rangefrom 10 to 70 μm.

Examples of the polymer film used as the base include films made of apolyester resin such as polyethylene terephthalate or aliphaticpolyester, or a polyolefin resin such as polypropylene or low-densitypolyethylene. Among these films, films made of polyester and low-densitypolyethylene are preferred. It is preferred that these polymer films beeasily removable from the photosensitive layer because they must beremoved from the photosensitive layer. The thickness of these polymerfilms is usually within a range from 5 to 100 μm, and preferably from 10to 30 μm.

The photosensitive dry film can be produced by the photosensitive layerforming step of applying a resist curable resin composition on a baseand drying the coating film. By forming a cover film on thephotosensitive layer formed, there can be produced a photosensitive dryfilm wherein the base, the photosensitive layer, and the cover film arelaminated in this sequence and the film is formed on both surfaces ofthe photosensitive layer. Since the cover film is peeled off when usingthe photosensitive dry film, the photosensitive layer can be protectedby forming the cover film on the photosensitive layer before use, andthus the photosensitive film is superior in shelf life. As the coverfilm, the same polymer film as that used in the base can be used. Thecover film and the base may be made of the same or different materials,and also have the same or different thicknesses.

To form an insulating protective film on the print circuit board usingthe photosensitive dry film, the laminating step of laminating thephotosensitive layer of the photosensitive dry film with the substrateis first conducted. When using the photosensitive dry film provided withthe cover film, the photosensitive layer is brought into contact withthe substrate after exposing the photosensitive layer by peeling off thecover film. Then, the photosensitive layer and the substrate arethermally contact-bonded at about 40 to 120° C. by a pressure roller orthe like, thereby laminating the photosensitive layer on the substrate.

Then, the exposure step of exposing the photosensitive layer to lightthrough a negative mask provided with a desired exposure pattern, thestep of peeling off the base from the photosensitive layer, thedevelopment step of developing by removing the non-exposure portion witha developing solution, and the thermocuring step of thermocuring thephotosensitive layer are conducted, thereby making it possible toproduce a printed circuit board wherein an insulating protective coatingfilm is formed on the surface of the substrate.

Using such a photosensitive dry film, an insulating resin layer may beformed between multi-layered print circuit boards.

The active light and the developing solution used in the exposure may bethe same as those described above.

The resist curable resin composition of the present invention hasexcellent film forming property and transparency and also has high flameresistance. When using a flame retardant, the resist curable resincomposition can form a cured film, which has excellent flame resistancewhile maintaining a beautiful appearance and high pliability, and isalso superior in photosensitivity and developability and meetperformances such as heat resistance, electrical insulating propertiesand adhesion to the wiring board. This cured film is particularlysuperior in transparency, flame resistance, pliability, electricalinsulating properties, and appearance. Therefore, it can form a goodinsulating protective film, which does not cause curling and is superiorin electrical performances, handling property and pliability, even whenused in a thin wiring board such as an FPC board.

EXAMPLES

The present invention will be described in detail by way of examples;however, the present invention is not limited to these examples.

Preparation Examples 1 to 3

Photosensitive prepolymers (A-1, A-2) having a carboxyl group weresynthesized.

Preparation Example 1 <EA-1>

In a flask equipped with a gas introducing tube, a stirrer, a coolingtube and a thermometer, 291 g of a bisphenol A type epoxy compoundmanufactured by Asahi Ciba Co., Ltd. (trade name: “ARALDITE® #2600”),129 g of bisphenol A and 0.20 g of triethylamine as a catalyst werecharged and then reacted at 150 to 160° C. for one hour to obtain abisphenol A type epoxy compound having a softening point of 97° C. andan epoxy equivalent of 1000 g/equiv. In the flask, 30 g of acrylic acid,0.45 g of monomethyl ether hydroquinone as an inhibitor and 1.65 g oftriphenylphosphine as an esterification catalyst were charged and thenreacted at 120° C. for 5 hours to obtain a reaction product having anacid value of 1 mg KOH/g. In the flask, 168 g of tetrahydrophthalicanhydride was charged and then reacted at 120° C. until the acid valuebecomes 100 mg KOH/g. This reaction required 3 hours. In the flask, 265g of ethylene glycol monomethyl ether acetate as a solvent and 114 g of“SUPER SOL #1800” manufactured by Mitsubishi Petroleum Co., Ltd. werecharged to obtain an epoxy acrylate resin (EA-1).

Preparation Example 2 <UA-1>

In a reaction vessel equipped with a stirrer, a thermometer, and acondenser, 2550 g (3 mol) of polytetramethylene glycol (manufactured byHODOGAYA CHEMICAL CO., LTD, PTMG-850, molecular weight: 850), 670 g (5mol) of dimethylolpropionic acid as a dihydroxyl compound having acarboxyl group, 1776 g (8 mol) of isophorone diisocyanate as apolyisocyanate, 238 g (2.05 mol) of 2-hydroxyethyl acrylate as a(meth)acrylate having a hydroxyl group, and each 1.0 g ofp-methoxyphenol and di-t-butylhydroxytoluene were charged. Heating wasstopped after heating to 60° C. while stirring, and 1.6 g of dibutyltindilaurate was added. Upon the beginning of a decrease in the temperatureof the reaction vessel, stirring was continued at 80° C. after heating.The reaction was completed after confirming by an infrared absorptionspectrum that an absorption spectrum (2280 cm⁻¹) of an isocyanate groupsdisappeared. As a result, a carboxyl group-containing photosensitiveprepolymer <UA-1>having a solid content of an acid value of 46 mg KOH/gand a solid content of 60% was obtained. The resulting prepolymer had aviscosity (25° C.) of 25,000 m·Pa.

Preparation Example 3 <UA-2>

In the same manner as in Preparation Example 1 <UA-1>, except that 800 g(1 mol) of polycarbonate diol (molecular weight: 800) containing a unitoriginating in hexamethylene carbonate and a unit originating inpentamethylene carbonate in a ratio of 1:1 was used as a polymer polyol,938 g (7 mol) of dimethylolpropionic acid was used as a dihydroxylcompound having a carboxyl group, 1998 g (9 mol) of isophoronediisocyanate was used as a polyisocyanate, and 238 g (2.05 mol) of2-hydroxyethyl acrylate was used as a (meth)acrylate having a hydroxylgroup, respectively, a urethane acrylate was synthesized. The resultingurethane acrylate <UA-2 > had a number-average molecular weight of18,000 and an acid value of 90 mg KOH/g.

Then, a resist curable resin composition was prepared.

Examples 1 to 10 and Comparative Examples 1 to 4

According to the formulation (parts by weight) shown in Table 1, <EA-1>,<UA-1> and <UA-2> prepared in Preparation Examples 1 to 3 as aphotosensitive prepolymer (A-1), a compound having an ethylenicallyunsaturated group (B), a photopolymerization initiator (C), a hydratedmetal compound (D1), a brominated epoxy compound (D2), a phosphate estercompound (D3), a thermocurable resin (E), a thermal polymerizationcatalyst (F), and a solvent were mixed to prepare a curable resincomposition. Although the solvent is used in the synthesis of thecomponent (A-1) and the preparation of the composition, the amount ofall components shown in Table 1 is expressed in terms of solid contentafter drying.

As the compound having an ethylenically unsaturated group (B), an epoxyacrylate: “RIPOXY SP-4010” (manufactured by SHOWA HIGHPOLYMER CO., LTD.)and a urethane acrylate: “EB1290K” (manufactured by DAICEL CHEMICALINDUSTRIES, LTD) were used.

As the photopolymerization initiator (C),2,4,6-trimethylbenzoylphenylphosphine oxide: “TPO” (manufactured by BASFCo.), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1(“IRGACURE®369”, manufactured by Ciba Specialty Chemicals Inc.) and1-hydroxycyclohexyl phenyl ketone (“IRGACURE® 184”, manufactured by CibaSpecialty Chemicals Inc.) were used.

As the hydrated metal compound (D1), aluminum hydroxide: “HIGILITE H-43STE” (manufactured by SHOWA DENKO K.K.), magnesium hydroxide: “KISUMA5A” (Kyowa Chemical Industry Co., Ltd.) and hydrotalcite: “DHT-4A”(manufactured by Kyowa Chemical Industry Co., Ltd.) were used. As thebrominated epoxy compound (D2), a bisphenol A type brominated epoxyresin: “EPIKOTE E-5050” (bromine content: 49% by weight, epoxyequivalent: 390, manufactured by Japan Epoxy Resin Co., Ltd.), abisphenol A type brominated epoxy acrylate “NEOPOL 8319S” (brominecontent: 41.1% by weight, manufactured by JAPAN U-PICA COMPANY, LTD.), acarboxyl group-containing bisphenol A type brominated epoxy acrylate:“NEOPOL 8318S” (bromine content: 32.2% and acid value of solid content:82.7 mg KOH/g, manufactured by JAPAN U-PICA COMPANY, LTD.) were used. Asthe phosphate ester compound (D2), an aromatic condensed phosphateester: “PX-200” (manufactured by DAIHACHI CHEMICAL INDUSTRY CO., LTD.)and orthophosphate ester: triphenyl phosphate TPP (manufactured byDAIHACHI CHEMICAL INDUSTRY CO., LTD.) were used.

As the thermocurable resin (E), a biphenyl type epoxy resin “YL6121H”(manufactured by Japan Epoxy Resin Co., Ltd.) was used. As the thermalpolymerization catalyst (F), melamine (manufactured by NISSAN CHEMICALINDUSTRIES, LTD) was used.

Test Example 1<Production of Photosensitive Dry Film>

Each of the resin compositions (viscosity: 5,000 mPa·s, 25° C.) preparedin Examples 1 to 10 and Comparative Examples 1 to 4 usingmethylcellosolve acetate as a solvent was applied on a 23 μm thick filmmade of polyethylene terephthalate using a doctor blade and was thendried at 80° C. for 7 minutes to form a photosensitive layer. Then, a 25μm thick polyethylene film (low-density polyethylene film) was laminatedthereon to produce a photosensitive dry film with a cover film. The filmthickness of the photosensitive layer after drying was 40±1 μm.

<Production of Laminate Specimen>

The cover film of the photosensitive dry film was peeled off and thephotosensitive layer was heated to 70° C., while a substrate forevaluation was heated to 60° C. and the photosensitive layer and thesubstrate for evaluation were laminated using a laminator to obtain alaminate specimen. As the substrate for evaluation, the followingsubstrates (1) and (2) were used.

(1) Substrate obtained by washing a printed board comprising a copperfoil (thickness: 35 μm) and a polyimide film (thickness: 50 μm)laminated on one surface of the copper foil [“UPISEL N”, manufactured byUBE INDUSTRIES, LTD.] with an aqueous 1% sulfuric acid solution, washingwith water and then drying in an air flow.

(2) 25 μm thick polyimide film [“CAPTON® 100H”, manufactured by DUPONT—TORAY CO., LTD.]

<Exposure, Development, and Thermocuring of Laminate Specimen>

Each of the resulting laminate specimens was exposed to light at a doseof 500 mJ/cm², using an exposing machine HMW-680GW [manufactured by OakCo., Ltd.] equipped with a metal halide lamp.

The non-exposure portion was removed by spraying an aqueous 1 wt %sodium carbonate solution at 30° C. over each laminate specimen for 30seconds and then spraying water at 30° C. for 30 seconds, therebyconducting the development. Then, a heat treatment was conducted at 150°C. for 30 minutes to obtain a copper-clad laminate (using a substrate(1) for evaluation) and a polyimide laminate (using a substrate (2) forevaluation).

In the production of the samples for evaluation of the photosensitivityand developability, exposure was conducted using a Stouffer 21 steptablet as a negative pattern. In the production of samples forevaluation of the soldering heat resistance, such a negative pattern isused, which enables a copper foil having a square of 1 cm×1 cm and aline/space of 1 mm/1 mm of a length of 2 cm to be remained within arange of 4 cm×6 cm. With respect to electrical insulating properties,IPC-C defined in IPC (Institute for Interconnecting and PackagingElectronic Circuit) Standard was used as the negative pattern. Thenegative pattern was not used in the production of other samples forevaluation.

<Evaluation of Physical Properties>

Physical properties were evaluated in the following manner. The resultsare shown in Table 2.

In the following respective evaluations, polyimide laminated plates wereevaluated with respect to the “flammability” and “flex resistance”,while laminates obtained by forming layers (thickness: 40 μm) made ofthe respective curable resins of Examples 1 to 8 and ComparativeExamples 1 to 4 on commercially available substrates (IPC-C) were usedwith respect to electrical insulating properties. With respect to otherevaluations, copper-clad laminates were evaluated.

Evaluation Items

Flammability

Specimens were made in the following manner. On both surfaces of apolyimide film (manufactured by DU PONT—TORAY CO., LTD., “CAPTON® 100H”)having a size of 25 μm in thickness and 200 mm×50 mm, a 40 μm thickcurable resin composition layer was formed. After exposing to UV at adose of 500 mJ/cm², the thick curable resin composition layer wasthermocured at 150° C. for 30 minutes. After conditioning at 70° C. for168 hours and subjecting to a solder shock treatment in a sand bath at260° C. for 10 seconds, samples for flame resistance testing wereobtained. With respect to the flammability, the flame resistance wasevaluated by the method in conformity to Underwriters Laboratories Inc.U.S.A. (abbreviated as UL) Tests For Flammability of Plastic Materials(94UL-VTM).

“VTM” and “NOT” described in Table 2 are based on the followingcriteria. “VTM-0”: Rating that meets all requirements described below

-   (1) Total flaming combustion time for each specimen after the first    burner flame application shall not exceed 10 seconds.-   (2) Total flaming combustion time for all 5 specimens of any set    shall not exceed 50 seconds after applying the tenth burner flame to    all 5 specimens of any set.-   (3) Flaming or glowing combustion shall not travel for more than 125    mm (mark line) of the specimen.-   (4) Cotton shall not ignite by flaming drips from any specimen.-   (5) Flaming and glowing combustion time for each specimen after    second burner flame application shall not exceed 30 seconds.-   (6) In case only one specimen among specimens (each group including    5 specimens) does not meet requirements or total flaming combustion    time ranges from 51 to 55 seconds, 5 specimens shall be tested and    all specimens shall meet the requirements (1) to (5).    “VTM-1”: Rating that meets all requirements described below-   (1) Total flaming combustion time for each specimen after the first    burner flame application shall not exceed 30 seconds.-   (2) Total flaming combustion time for all 5 specimens of any set    shall not exceed 250 seconds after applying the tenth burner flame    to all 5 specimens of any set.-   (3) Flaming or glowing combustion shall not travel for more than 125    mm (mark line) of the specimen.-   (4) Cotton shall not ignite by flaming drips from any specimen.-   (5) Flaming and glowing combustion time for each specimen after    second burner flame application shall not exceed 60 seconds.-   (6) In case only one specimen among specimens (each group including    5 specimens) does not meet requirements or total flaming combustion    time ranges from 251 to 255 seconds, 5 specimens shall be tested and    all specimens shall meet the requirements (1) to (5).    “VTM-2”: Rating that meets all requirements described below-   (1) Total flaming combustion time for each specimen after the first    burner flame application shall not exceed 30 seconds.-   (2) Total flaming combustion time for all 5 specimens of any set    shall not exceed 250 seconds after applying the tenth burner flame    to all 5 specimens of any set.-   (3) Flaming or glowing combustion shall not travel for more than 125    mm (mark line) of the specimen.-   (4) Cotton may ignite by flaming drips from any specimen.-   (5) Flaming and glowing combustion time for each specimen after    second burner flame application shall not exceed 60 seconds.-   (6) In case only one specimen among specimens (each group including    5 specimens) does not meet requirements or total flaming combustion    time ranges from 251 to 255 seconds, 5 specimens shall be tested and    all specimens shall meet the requirements (1) to (5).    “NOT”: Case where specimens do not pass all ratings    Photosensitivity

After laying a Stouffer 21 step tablet as a negative pattern on thesample, the sample was exposed to light and developed. Thephotosensitivity of a curable resin composition was evaluated bymeasuring the number of steps of the step tablet of the photocured filmformed on the resulting copper-clad laminate. The photosensitivity isexpressed by the number of steps of the step tablet. The larger thenumber of steps of the step tablet, the higher the photosensitivity.

Developability

In the evaluation of the photosensitivity, the sample was developedunder the conditions of a temperature of 30° C. and a spray pressure of2 kg/cm² for one minute, using an aqueous 1 wt % sodium carbonatesolution as a developing solution. The state of the coating film wasvisually judged. Symbols in Table 2 are as follows.

-   ∘: completely developed-   Δ: slight development residue exists-   ×: development residue exists-   Flex resistance

A polyimide laminate was folded by 180 degrees while making a cured filmmade of a photosensitive layer to face inside. It was examined whetheror not whitening of the cured film occurred.

-   ∘: no whitening of cured film-   ×: whitening of cured film occurred    Soldering Heat Resistance

In conformity to the method defined in JIS C-6481, a copper-cladlaminate was floated on a solder bath at 260° C. for 10 seconds (1cycle) and this cycle was repeated three times. Then, “blister” andadhesion of the cured film were generally evaluated.

-   ⊚: no change was observed-   ∘: slight change-   Δ: less than 10% of cured film was peeled off-   ×: entire cured film was peeled off    Electrical Insulating Properties (Insulating Resistance)

On IPC-C (comb-shaped pattern) of a commercially available substrate(IPC Standard), each of curable resin composition layers of Examples 1to 8 and Comparative Examples 1 to 4 was formed. The resulting laminatewas allowed to stand in an atmosphere at a temperature of 85° C. and arelative humidity of 100% for 192 hours and the insulating propertieswere evaluated by measuring values of the insulating resistance beforeand after the treatment. In conformity to JIS C5012, DC 100 V wasapplied to the substrates before and after the treatment and, aftermaintaining for one minute, values of the insulating resistance weremeasured by an insulation resistance tester in the state where thevoltage is applied.

Test Example 2

<Production of Laminate Specimen>

Each of the curable resin compositions (viscosity: 20,000 mPa·s)prepared in Examples 1, 2, 8, and 9 and Comparative Examples 1 and 2using carbitol acetate as a solvent was applied on a substrate forevaluation by a screen printing method so that the film thickness afterdrying becomes about 40 μm, using a 150 mesh polyester plate. Thecurable resin composition applied was dried at 70° C. for 30 minutes toproduce a laminated specimen. The final film thickness of thephotosensitive layer was 40±2 μm. As the substrate for evaluation, thesubstrates (1) and (2) described above were used. These substrates werealso evaluated in the same manner as in Test Example 1. The results areshown in Table 2.

TABLE 1 Examples 1 2 3 4 5 6 7 8 9 10 (A) EA-1 34.0 34.0 34.0 20.0 UA-110.0 30.0 30.0 30.0 16.0 16.0 16.0 UA-2 12.0 12.0 8.0 (B) Epoxy acrylateSP-4010 8.0 8.0 8.0 Urethane acrylate EB-1290K 14.0 14.0 14.0 14.0 14.08.0 8.0 (C) Photopolymerization initiator 1 (TPO) 2.0 2.0 2.0 1.0 1.01.0 1.0 1.0 1.0 1.0 Photopolymerization initiator 2 (EAB-F) 2.0 2.0 2.01.0 1.0 1.0 1.0 1.0 1.0 1.0 Photopolymerization initiator 3 (IRGACURE ®184) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 (D1) Aluminum hydroxide 18.0 18.0 22.022.0 22.0 22.0 22.0 Magnesium hydroxide 18.0 22.0 22.0 22.0 Hydrotalcite18.0 (D2) EPIKOTE5050 18.0 18.0 18.0 18.0 22.0 22.0 22.0 22.0 NEOPOL8319S 14.0 NEOPOL 8318S 18.0 (D3) PX-200 4.5 4.5 4.5 4.5 5.0 5.0 5.0 4.04.0 TPP 5.0 (E) Epoxy resin 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.010.0 (F) Melamine 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 ComparativeExamples 1 2 3 4 (A) EA-1 34.0 34.0 UA-1 30.0 16.0 UA-2 12.0 (B) Epoxyacrylate SP-4010 8.0 8.0 Urethane acrylate EB-1290K 14.0 14.0 (C)Photopolymerization initiator 1 (TPO) 2.0 2.0 1.0 1.0Photopolymerization initiator 2 (EAB-F) 2.0 2.0 1.0 1.0Photopolymerization initiator 3 (IRGACURE ® 184) 1.0 1.0 (D1) Aluminumhydroxide 18.0 22.0 22.0 Magnesium hydroxide 18.0 Hydrotalcite (D2)EPIKOTE 5050 18.0 22.0 NEOPOL 8319S NEOPOL 8318S (D3) PX-200 5.0 TPP (E)Epoxy resin 10.0 10.0 10.0 10.0 (F) Melamine 1.0 1.0 1.0 1.0

TABLE 2 Insulating resistance Soldering heat Before After FlammabilityPhoto- Develop- Flex resistance treatment treatment 94VTM sensitivityability resistance 1 cycle 3 cycles (Ω) (Ω) Test Example 1 (Film)Example 1 VTM-0 12 ◯ ◯ ⊚ ⊚ 1.6 × 10¹⁴ 2.3 × 10¹¹ Example 2 VTM-0 11 ◯ Δ⊚ ⊚ 8.1 × 10¹³ 4.4 × 10¹⁰ Example 3 VTM-0 10 ◯ ◯ ⊚ ⊚ 1.6 × 10¹⁴ 8.1 ×10¹⁰ Example 4 VTM-0 11 ◯ ◯ ⊚ ⊚ 3.8 × 10¹⁴ 4.5 × 10¹⁰ Example 5 VTM-0 9◯ ◯ ⊚ ◯ 1.5 × 10¹⁴ 2.9 × 10¹¹ Example 6 VTM-0 9 ◯ ◯ ⊚ Δ 4.6 × 10¹⁴ 8.8 ×10⁹  Example 7 VTM-0 8 ◯ ◯ ⊚ ◯ 4.4 × 10¹⁴ 6.9 × 10¹⁰ Example 8 VTM-0 10◯ ◯ ⊚ ◯ 7.5 × 10¹³ 2.9 × 10¹² Example 9 VTM-0 14 ◯ ◯ ⊚ ⊚ 3.0 × 10¹³ 8.7× 10¹¹  Example 10 VTM-0 14 ◯ Δ ⊚ ⊚ 4.1 × 10¹³ 1.6 × 10¹² ComparativeExample 1 NOT 12 ◯ X ⊚ Δ 8.0 × 10¹³ 4.6 × 10¹⁰ Comparative Example 2 NOT12 ◯ X ⊚ ⊚ 3.8 × 10¹⁴ 2.2 × 10¹¹ Comparative Example 3 NOT 8 ◯ X ⊚ Δ 8.0× 10¹³ 4.9 × 10¹⁰ Comparative Example 4 NOT 10 ◯ ◯ ◯ X 5.6 × 10¹³ 4.6 ×10¹⁰ Test Example 2 (Ink) Example 1 VTM-0 13 ◯ ◯ ⊚ ◯ 2.1 × 10¹⁴ 8.3 ×10¹⁰ Example 2 VTM-0 12 ◯ ◯ ⊚ ◯ 1.7 × 10¹³ 4.9 × 10¹¹ Example 8 VTM-0 10◯ ◯ ⊚ ◯ 7.5 × 10¹³ 6.0 × 10¹¹ Example 9 VTM-0 10 ◯ ◯ ⊚ ◯ 3.0 × 10¹³ 8.7× 10¹¹ Comparative Example 1 NOT 12 ◯ X ⊚ Δ 5.0 × 10¹⁴ 8.6 × 10¹⁰Comparative Example 2 NOT 12 ◯ X ⊚ ◯ 8.9 × 10¹² 9.6 × 10⁹ 

Examples 11 to 18 and Comparative Examples 5 to 8

According to the formulation (parts by weight) shown in Table 3, <EA-1>,<UA-1> and <UA-2> prepared in Preparation Examples 1 to 3 as aphotosensitive prepolymer (A-2) having a carboxyl group, a compoundhaving an ethylenically unsaturated group (B), a photopolymerizationinitiator (C), a hydrated metal compound, a brominated epoxy compound, aphosphate ester compound, a thermocurable resin (E) and a thermalpolymerization catalyst (F) were mixed to prepare a curable resincomposition. Although the solvent is used in the synthesis of thephotosensitive prepolymer and the preparation of the composition, theamount of all components shown in Table 3 is expressed in terms of solidcontent after drying.

As the compound having an ethylenically unsaturated group (B), adipentaerythritol hexaacrylate “M-400” (manufactured by TOAGOSEI CO,LTD.) and a urethane acrylate “EB1290K” (manufactured by DAICEL CHEMICALINDUSTRIES, LTD) were used.

As the photopolymerization initiator (C),2,4,6-trimethylbenzoylphenylphosphine oxide “TPO” (photopolymerizationinitiator 1) manufactured by BASF CO., 2-benzyl-2-dimethylamino1-(4-morpholinophenyl)-butanone-1 (trade name: “IRGACURE® 369”)(photopolymerization initiator 2) manufactured by Ciba SpecialtyChemicals Inc. and 1-hydroxycyclohexyl phenyl ketone (trade name:“IRGACURE® 184”) (photopolymerization initiator 3) manufactured by CibaSpecialty Chemicals Inc. were used.

<Aluminum Hydroxide 1, 2 and 3>

As the hydrated metal compound, an aluminum hydroxide “HIGILITE H-43M”(manufactured by SHOWA DENKO K.K.) [average particle diameter determinedby calculating from a ratio of a major axis to aminor axis afterobserving a secondary electron image at an acceleration voltage of 20 kVusing a scanning electron microscope (JSM-5500LV, manufactured byJEOL):0.6 μm] was used. As the surface treating agent, three kinds of(1) stearic acid (amphipathic compound: reagent manufactured by JUNSEICHEMICAL CO., LTD.), (2) 3-glycidoxypropyltrimethoxysilane “A-187”(silane coupling agent, manufactured by Nippon Unicar Co., Ltd.), and(3) 3-mercaptopropyltrimethoxysilane “A-189” (silane coupling agent,manufactured by Nippon Unicar Co., Ltd.) were used. Aluminum hydroxidessurface-treated with the surface treating agents (1) to (3) arerespectively designated aluminum hydroxides 1, 2 and 3.

The surface treatment was conducted in the following manner. When usingstearic acid, aluminum hydroxide and stearic acid (3% by weight) werefed in a 20 L Henschel mixer and stearic acid was dissolved by heatingto 100° C.±5° C. while stirring, thereby surface-treating the aluminumhydroxide.

In the case of the silane coupling agent, the silane coupling agent wasweighed in the amount of 1% by weight based on the amount of aluminumhydroxide and was then diluted four times with a solution of water andan alcohol in a ratio of 1/9 (vol/vol). A 10 wt % water dispersion ofaluminum hydroxide was prepared and the silane coupling agent wasintroduced while stirring. After completely introducing the silanecoupling agent, the mixture was stirred for 5 hours, filtered and thenvacuum-dried at 80° C. for 12 hours to obtain a sample. With respect to3-glycidoxypropyltrimethoxysilane “A-187”, the treatment was conductedby heating the Henschel mixer to 80° C. after introducing a silanecoupling agent without using a diluent.

<Hydrotalcite 1 and 2>

-   (1) Using magnesium nitrate, aluminum nitrate and sodium hydroxide    as a raw material, a hydrotalcite was synthesized according to the    method described in the literature [S. Miyata, Clays & Clay    Minerals, 23, 369–375 (1975)]. The hydrotalcite was aged at a    dropping rate of sodium hydroxide of 50 ml/min at 60° C. for 6 hours    to obtain a hydrotalcite (non-treated product) of the structural    formula: [Mg_(0.7)Al_(0.3)(OH)₂(NO₃)_(1.0).0.6H₂O] which contains    nitric acid ions as interlayer ions. With respect to the particle    size of this single crystal grain, the average particle diameter    determined by calculating from a ratio of a major axis to aminor    axis after observing a secondary electron image at an acceleration    voltage of 120 kV using a transmission electron microscope (CX200,    manufactured by JEOL) was 0.4 μm.

This hydrotalcite crystal was mixed with 3% by weight of stearic acidand the mixture was heated to 100° C. while stirring in a Henschelmixer, and then stirred for 5 minutes to obtain a sample (hydrotalcite1).

-   (2) An aqueous solution of D,L-phenylalanine (reagent, manufactured    by JUNSEI CHEMICAL CO., LTD.) having a pH of 10 adjusted by sodium    hydroxide was added dropwise in an aqueous mixed solution of    magnesium nitrate and aluminum nitrate in a molar ratio of 3:1,    thereby to coprecipitate a hydrotalcite which contains D,    L-phenylalanine ions as interlayer ions. Sodium hydroxide was    appropriately added dropwise in the mixed solution and, after    maintaining at pH 10 and aging at 60° C. for 6 hours, washing and    filtration were repeated. Then, the resulting product was dried and    ground to obtain a sample (hydrotalcite 2).

As the brominated epoxy compound, a bisphenol A type brominated epoxyresin “EPIKOTE E-5050” (manufactured by Japan Epoxy Resin Co., Ltd.) wasused. As the phosphate ester compound, an aromatic condensed phosphateester “PX-200” (manufactured by DAIHACHI CHEMICAL INDUSTRY CO., LTD.)was used.

As the thermocurable resin (E), a biphenyl type epoxy resin “YL6121H”(manufactured by Japan Epoxy Resin Co., Ltd.) was used. As the thermalpolymerization catalyst (F), melamine (manufactured by NISSAN CHEMICALINDUSTRIES, LTD.) was used.

<Production of Photosensitive Dry Film>

With respect to Examples 11 to 18 and Comparative Examples 5 to 8,photosensitive dry films were produced in the same manner as in Examples1 to 10 and Comparative Examples 1 to 4.

<Production of Laminate Specimen>

With respect to Examples 11 to 18 and Comparative Examples 5 to 8,laminate specimens were produced in the same manner as in Examples 1 to10 and Comparative Examples 1 to 4.

<Exposure, Development, and Thermocuring of Laminate Specimen>

The respective laminate specimens thus obtained were exposed to light ata dose of 500 mJ/cm² using an exposing machine HMW-680GW [manufacturedby Oak Co., Ltd.] equipped with a metal halide lamp.

The non-exposed portion was removed by developing with an aqueous 1 wt %sodium carbonate solution at 30° C. for one minute. After thedevelopment, a heat treatment was conducted at 150° C. for 30 minutes toobtain a copper-clad laminate (using a substrate (1) for evaluation) anda polyimide laminate (using a substrate (2) for evaluation).

In the production of the samples for evaluation of the photosensitivityand developability, exposure was conducted using a 21 step tabletmanufactured by Hitachi Chemical Co., Ltd., as a negative pattern.

<Evaluation of Physical Properties>

Physical properties were evaluated in the following manner. The resultsare shown in Table 4.

Flammability

In the same manner as in Examples 1 to 10, Comparative Examples 1 to 4,except that a test was once conduced using five specimens (1 set), andfurthermore, the total time required to fire extinguishing of fivespecimens and the number of the fire extinguishing test of fivespecimens were counted for comparing the flame resistance.

Photosensitivity

After laying a 21 step tablet manufactured by Hitachi Chemical Co.,Ltd., as a negative pattern on the sample, the sample was exposed tolight at a dose of 500 mJ/cm². Then, the non-exposure portion wasremoved by developing with an aqueous 1 wt % sodium carbonate solutionat 30° C. for one minute and the photosensitivity of a curable resincomposition was evaluated by measuring the number of steps of the steptablet of the photocured film formed on the resulting copper-cladlaminate.

Developability

With respect to Examples 11 to 18 and Comparative Examples 5 to 8,evaluation was conducted in the same manner as in Examples 1 to 10 andComparative Examples 1 to 4.

Folding Resistance

The sample was produced by laminating a resist on both surfaces of a 25μm thick polyimide film and cutting a specimen obtained by exposure,development, and curing of the sample into pieces having a width of 15mm and a length of 110 mm. In conformity to the folding resistance testdefined in JIS C5016, the folding resistance was evaluated by using aMIT flex fatigue testing machine, Model S, manufactured by Toyo SeikiCo., Ltd. The sample was mounted to a folding device (distance: 0.25 mm,R=0.38) and was repeatedly folded from side to side at a load of 4.9 N,folding angle of 135° and a rate of 175 cpm.

The folding test was temporarily stopped every 10 times of folding andthe folded portion of each sample was observed by a microscope. Themaximum number of times of folding was counted until the resist film wascracked.

TABLE 3 Examples Comparative Examples 11 12 13 14 15 16 17 18 5 6 7 8(A) EA-1 34.0 34.0 34.0 — — 34.0 34.0 — 34.0 34.0 — — UA-1 — — — 16.016.0 — — 16.0 — — 16.0 16.0 UA-2 — — — 12.0 12.0 — — 12.0 — — 12.0 12.0(B) Dipenaerythritol (M-400) 8.0 8.0 8.0 3.0 3.0 8.0 8.0 3.0 8.0 8.0 3.03.0 Urethane acrylate (EB1290K) — — — 6.0 6.0 — — 6.0 — — 6.0 6.0 (C)Photopolymerization initiator 1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.01.0 1.0 Photopolymerization initiator 2 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.01.0 1.0 1.0 1.0 Photopolymerization initiator 3 1.0 1.0 1.0 1.0 1.0 1.01.0 1.0 1.0 1.0 1.0 1.0 (D1) Aluminum hydroxide 1 16.0 — — — — — — — — —— — Aluminum hydroxide 2 — 16.0 — 16.0 — — — — — — — — Aluminumhydroxide 3 — — 16.0 — 16.0 — — — — — — — Aluminum hydroxide (H-43M) — —— — — — — — 16.0 — 16.0 — Hydrotalcite 1 — — — — 20.0 — — — — — —Hydrotalcite 2 — — — — — — 20.0 20.0 — — — — Hydrotalcite (untreatedproduct) — — 18.0 — — — — — — 20.0 — 20.0 (D2) Brominated epoxy resin(E-5050) 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0(D3) Phosphate ester (PX-200) 6.0 6.0 6.0 3.4 3.4 6.0 6.0 3.4 6.0 6.03.4 3.4 (E) Epoxy resin (YL6121H) 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.06.0 6.0 6.0 (F) Melamine 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0

TABLE 4 Combustion test Folding Fire extinguishing test Total flaming94VTM- Photo- Develop- resistance Number of pieces/5 time (sec) classsensitivity ability (times) Example 11 5 5.2 VTM-0 14 ◯ 80 Example 12 57.4 VTM-0 14 ◯ 80 Example 13 5 8.2 VTM-0 12 ◯ 70 Example 14 5 17.4 VTM-012 ◯ 150 Example 15 5 15.3 VTM-0 12 ◯ 100 Example 16 5 14.8 VTM-0 13 ◯80 Example 17 5 26.9 VTM-0 14 ◯ 90 Example 18 5 23.3 VTM-0 11 ◯ 220Comparative 5 20.7 VTM-0 14 ◯ 20 Example 5 Comparative 5 42.8 VTM-0 12 ◯40 Example 6 Comparative 5 45.5 VTM-0 12 ◯ 60 Example 7 Comparative 353.6 NOT 10 ◯ 60 Example 8

INDUSTRIAL APPLICABILITY

The resist curable resin composition of the present invention can form aprotective film, which has good photosensitivity and alklalidevelopability and also has excellent flame resistance, pliability, andsoldering heat resistance. Particularly, it can be preferably used toform a cover-layer for FPC, or a solder resist.

1. A resist curable resin composition comprising a resist curable resinmaterial, a hydrated metal compound, a phosphate ester compound, and abrominated epoxy compound, wherein the hydrated metal compound issurface-treated with a surface treating agent having at least one of anamphipathic property and a polarity, the resist curable resin materialis a photocurable resin material comprising a photosensitive prepolymerhaving an ethylenically unsaturated terminal group originating in anacrylic monomer, a compound having an ethylenically unsaturated groupexcluding the photosensitive prepolymer, and a photopolymerizationinitiator, and the brominated epoxy compound is a tetrabromobisphenol Atype epoxy resin having an epoxy equivalent of 200 to 3000 and a brominecontent of 40 to 60% by weight or a polyfunctional epoxy (meth)acrylatecompound having a bromine content of 30 to 60% by weight.
 2. A resistcurable resin composition according to claim 1, wherein thephotosensitive prepolymer has both a carboxyl group and at least twoethylenically unsaturated bonds in a molecule.
 3. A resist curable resincomposition according to claim 1, wherein the photosensitive prepolymeris an epoxy (meth)acrylate compound having a carboxyl group.
 4. A resistcurable resin composition according to claim 3, wherein the epoxy(meth)acrylate compound having a carboxyl group has a solid content ofan acid value of 10 mg KOH/g or more.
 5. A resist curable resincomposition according to claim 1, wherein the photosensitive prepolymeris a urethane (meth)acrylate compound having a carboxyl group.
 6. Aresist curable resin composition according to claim 5, wherein theurethane (meth)acrylate compound having a carboxyl group has a solidcontent of an acid value of 5 to 150 mg KOH/g.
 7. A resist curable resincomposition according to claim 1, wherein the photosensitive prepolymercontains a urethane (meth)acrylate compound having a carboxyl group,which has a solid content of an acid value of 5 mg KOH/g or more andless than 60 mg KOH/g, and a urethane (meth)acrylate compound having acarboxyl group, which has a solid content of an acid value of 60 mgKOH/g or more and 150 mg KOH/g or less.
 8. A resist curable resincomposition according to claim 1, containing a thermocurable resin and athermal polymerization catalyst.
 9. A resist curable resin compositionaccording to claim 1, wherein the resist curable resin material is athermocurable resin material.
 10. A resist curable resin compositionaccording to claim 1, containing an organic solvent.
 11. A resistcurable resin composition according to claim 1, wherein endothermy ofthe hydrated metal compound is 400 J/g or higher upon thermolysis.
 12. Aresist curable resin composition according to claim 1, wherein thehydrated metal compound is at least one of aluminum hydroxide andmagnesium hydroxide.
 13. A resist curable resin composition according toclaim 1, wherein the hydrated metal compound is incorporated in theamount of 10 to 100 parts by weight based on 100 parts by weight of theresist curable resin material.
 14. A resist curable resin compositionaccording to claim 1, wherein the brominated epoxy compound isincorporated in the amount of 10 to 80 parts by weight based on 100parts by weight of the resist curable resin material.
 15. A resistcurable resin composition according to claim 1, wherein the phosphateester compound has pentavalent phosphorus atoms.
 16. A resist curableresin composition according to claim 1, wherein the phosphate estercompound has an aromatic group.
 17. A resist curable resin compositionaccording to claim 1, wherein the phosphate ester compound isincorporated in the amount of 0.5 to 40 parts by weight based on 100parts by weight of the resist curable resin material.
 18. A resistcurable resin composition according to claim 1, having a viscosity of500 to 500,000 mPa·s (25° C.).
 19. A resist curable resin compositionaccording to claim 1, wherein the surface treating agent having anamphipathic property is selected from the group consisting of asaturated fatty acid having 6 or more carbon atoms; an unsaturated fattyacid and a salt thereof; primary amine, secondary amine, and tertiaryamine, and a salt thereof; a quaternary ammonium salt; an aminecompound; and an amino acid derivative.
 20. A resist curable resincomposition according to claim 1, wherein the surface treating agenthaving a polarity is selected from the group consisting of titanatecoupling agent, aluminum coupling agent, zircoaluminate coupling agent,and silane coupling agent.
 21. A resist curable resin compositionaccording to claim 1, wherein the hydrated metal compound is ahydrotalcite or hydrotalcite-based compound which has a layered crystalstructure and has an organic anion between crystal layers.
 22. A resistcurable resin composition according to claim 21, wherein the organicanion is selected from the group consisting of amino acid,sulfur-containing compound, and nitrogen-containing heterocycliccompound, and a salt thereof.
 23. A resist curable resin compositionaccording to claim 1, wherein the hydrated compound has an averageparticle diameter of 0.1 to 30 μm.
 24. A cured article obtained bycuring the resist curable resin composition of claim
 1. 25. Inkcomprising the resist curable resin composition of claim 1 and acolorant.
 26. A method for curing a resist curable resin composition,which comprises the steps of: applying the resist curable resincomposition of claim 1 or the ink of claim 25 on a substrate in athickness of 10 to 100 μm, drying at a temperature within a range from60° C. to 100° C. for 5 to 30 minutes to form a film having a thicknessof 5 to 70 μm, exposing the film, developing the film exposed andthermocuring the film developed.
 27. A dry film comprising a base and aphotosensitive layer made of the resist curable resin composition ofclaim 1 formed on a base.
 28. A dry film according to claim 27, whereinthe base is a film made of polyester or polyethylene.
 29. A method forproducing a printed circuit board, which comprises: a laminating step oflaminating the photosensitive layer of the dry film of claim 27 with asubstrate, an exposure step of exposing the photosensitive layer tolight, a development step which follows the exposure step, and athermocuring step of thermocuring the photosensitive layer.
 30. A methodfor producing a photosensitive dry film, which comprises the step ofapplying the resist curable resin composition of claim 1 on a base anddrying the resist curable resin composition to form a photosensitivelayer.
 31. An insulating protective film made of the resist curableresin composition of claim
 1. 32. A printed circuit board comprising theinsulating protective film of claim
 31. 33. A flexible printed circuitboard comprising the insulating protective film of claim
 31. 34. Aresist curable resin composition comprising a resist curable resinmaterial, a hydrated metal compound, and a brominated epoxy compound,wherein the hydrated metal compound is surface-treated with a surfacetreating agent having at least one of an amphipathic property and apolarity, and the brominated epoxy compound is a tetrabromobisphenol Atype epoxy resin having an epoxy equivalent of 200 to 3000 and a brominecontent of 40 to 60% by weight.
 35. A resist curable resin compositioncomprising a resist curable resin material, a hydrated metal compound,and a brominated epoxy compound, wherein the hydrated metal compound issurface-treated with a surface treating agent having at least one of anamphipathic property and a polarity, and the brominated epoxy compoundis a polyfunctional epoxy (meth)acrylate compound having a brominecontent of 30 to 60% by weight.